Two Australian teenagers allegedly recruited as "mules" to smuggle heroin from Hong Kong to Sydney face 20 years in jail if convicted of drug charges.

A 17-year-old girl and 15-year-old boy arrested and detained in Hong Kong have been charged under local law with possessing a prohibited drug.

A 21-year-old man from Cabramatta, in Sydney's south-west, has also been arrested and charged with drug trafficking offences.

NSW police said the two juveniles, both Australian citizens, were allegedly recruited as "mules" to smuggle a kilogram of heroin, with an estimated street value of $1 million, from Hong Kong to Sydney.

They were arrested inside a Hong Kong hotel room after local police allegedly discovered 114 packages containing the drug wrapped in the fingers of gloves and condoms.

Police allege the teenagers were planning to swallow the packages and return to Sydney on a commercial flight this week.

The 21-year-old man was also arrested at the hotel.

A fourth man has been detained in Hong Kong over weapons related charges. It is unclear whether he is linked to the drug smuggling attempt.

A Department of Foreign Affairs and Trade (DFAT) spokesman today said the four Australians have been offered consular assistance in Hong Kong.

"We are aware of two Australian males, one is a minor, and a female, also a minor, from Sydney have been detained in Hong Kong on drug-related charges," the spokesman said.

"A third Australian male also from Sydney has been detained on weapons-related charges.

"Consular officials from the Australian consulate general in Hong Kong have been in contact with them and have offered consular assistance.

"The next of kin are also in the process of being contacted and offered consular services."

The names of the Australians have not been released.

Australian officials were checking on the welfare of group and ensuring they had legal representation, the spokesman said.

The men who allegedly recruited the teenagers have also been arrested by South East-Asian Crime Squad (SEAC) detectives in Sydney and charged with conspiracy to import a prohibited import.

Two 21-year-old men were arrested at 7.15pm (AEST) yesterday at a service station in Yagoona, in the city's south-west.

They were due to appear in Burwood Local Court today.

SEAC Commander Deborah Wallace said any matter involving juveniles couriering drugs was "shocking".

"I can understand, I suppose, that people who are older make decisions based on a whole range of things, but to prey on juveniles to me escalates this offence a lot," Det Supt Wallace told reporters.

Simon Parry, Hong Kong

A 15-YEAR-OLD McDonald's worker and a 17-year-old trainee hairdresser caught with a $1million haul of drugs in a Hong Kong hotel had allegedly agreed to act as "mules" to carry the illicit cargo into Australia by swallowing heroin-filled condoms at $200 for each package.

The pair, Chris Vo, 15, and Rachel Ann Diaz, 17, now face 20 years in a Hong Kong prison.

Sources told The Australian Vo allegedly agreed to swallow "at least 20" condoms.

Vo was arrested in a Hong Kong hotel room last Tuesday with Diaz, who is also alleged to have been recruited as a drugs mule by the same Chinese-run syndicate based in Sydney and planned to swallow a similar number of heroin-filled condoms.

Diaz was being held yesterday in a high-security Hong Kong women's prison that houses prostitutes from China as well as some of the former British colony's most notorious female gangsters.

Drugs squad officers burst into the teenagers' room at the shabby Imperial Hotel in Hong Kong's Tsim Sha Tsui backpacker district, where they allegedly found dozens of condoms and glove fingers filled with heroin, with an estimated street value of $1million.

The pair had been due to board a flight back to Sydney from Hong Kong later that evening after spending a week in the three-star hotel, which was popular with backpackers and visitors from China.

A third Australian, 21-year-old Hutchison Tran, who is thought to have brought the heroin to their hotel room, was arrested with the two teenagers. He arrived in Hong Kong before the teenagers and is suspected of setting up the smuggling operation.

Hong Kong police, tipped off by their Sydney counterparts, launched a simultaneous raid on an apartment in nearby Yau Ma Tei where they arrested a fourth Australian, Qi Zhen Peng, 22, who was armed with an air pistol and a knife.

NSW police Southeast Asian Crime Squad Commander, Detective Superintendent Deborah Wallace, said police alerted Hong Kong authorities after learning that the teens were allegedly about to start swallowing 114 drug-filled condoms.

"There was a real risk to the teenagers if one of the packages burst," Superintendent Wallace said.

A kilogram of heroin with a Hong Kong street value of $1million costs less than $60,000 in Sydney.

Vo and Diaz are understood to have flown to Hong Kong alone, where they met Tran and Peng. They arrived in Hong Kong a week before their arrest.

A spokesman for the Department of Foreign Affairs and Trade said last night a bail application would be made on behalf of the two teenagers on Friday. He declined to say if the application would be for the teenagers to be allowed to return to Australia, saying: "Any bail conditions would have to be applied by the court."

He said the department was extending "the full range of consular services to the families involved".

At a court hearing last Friday, Vo and Tran were charged with trafficking a dangerous drug. They were remanded in custody until June 24.

Additional reporting: Jonathan Porter

Police allege that the men recruited a 17-year-old girl and a 15-year-old boy to act as "drug mules" and smuggle heroin from Hong Kong to Sydney.

They say that authorities in Hong Kong have arrested the teenagers who are both Australian citizens. They were arrested at an hotel where 114 packets of heroin were alleged to have been found.

They have been charged with drug offences.

Last night, police in Sydney took two men into custody at Chullora in the city's south-west. The men were questioned by officers from the South-East Asian Crime Squad.

In Burwood Local Court today, the men accused of conspiring to smuggle the drug into Australia were remanded in custody.

They will return to court in May.

Sun Won Kim and Bao Zhang, both aged 21, appeared in Burwood Local Court today charged with conspiracy to import a prohibited drug.

They were arrested at a service station in Yagoona in south-western Sydney last night over an alleged conspiracy to import heroin.

The teenagers and a 21-year-old Cabramatta man, all Australian citizens, were arrested in a Hong Kong hotel room last Monday.

A fourth man has been detained in Hong Kong over weapons-related charges. It is unclear whether he is linked to the alleged drug smuggling attempt.

Police allegedly found 114 packages containing heroin wrapped in the fingers of rubber gloves and condoms inside the hotel room.

New South Wales police said the heroin had an estimated street value of $1 million.

The teenagers have been charged under Hong Kong law with possessing a prohibited drug and face 20 years in jail if convicted.

A Department of Foreign Affairs and Trade (DFAT) spokesman today said the four Australians have been offered consular assistance in Hong Kong.

"We are aware of two Australian males, one is a minor, and a female, also a minor, from Sydney have been detained in Hong Kong on drug-related charges," the spokesman said.

"A third Australian male also from Sydney has been detained on weapons-related charges.

"Consular officials from the Australian consulate general in Hong Kong have been in contact with them and have offered consular assistance.

"The next of kin are also in the process of being contacted and offered consular services."

Mr Kim and Mr Zhang did not apply for bail and were remanded in custody by Magistrate Paul Cloran to appear in Central Local Court on May 31.