AFGHAN authorities are continuing negotiations to release an Italian aid worker in her fifth day of captivity after identifying her abductor, President Hamid Karzai said today.

"We are working on releasing her safely and we want her release for the good of Afghanistan, Italy and aid work in Afghanistan," Mr Karzai told reporters at a news conference in Kabul ahead of his visit to Washington.

He said security forces had identified the kidnapper and the hostage-taking did not appear to be the work of an organised group of Islamic militants.

"Whoever has kidnapped her has feuded with Afghanistan and we don't consider it the work of a group. We know who has done it and why, but I won't talk about it now," he said.

Clementina Cantoni, 32, who works for CARE International, was dragged from her car by armed men in the Qala-e-Mosa district of central Kabul on Tuesday.

The Italian aid worker had been in Afghanistan since 2002 and had overseen a project which provided food and employment for more than 10,000 Afghan widows.

"A couple of nights ago those women who she had helped, demonstrated and seriously asked for the release of this woman. She served Afghanistan," Mr Karzai said.

Confusion has surrounded the abduction with the alleged kidnapper who identifies himself as Timur Shah calling various media outlets with differing demands for her release and overnight making a claim that he had killed her.

Afghan authorities denied Shah's claim and said negotiations were continuing and she was still alive.

In October last year, three foreign United Nations workers were seized in central Kabul at gunpoint and held for a month before being released unharmed.

The abduction of the UN workers in Kabul is thought to have been the work of Islamic militants in league with a criminal gang, but Ms Cantoni's abduction appears to be linked to worsening security and rising crime in the country.

Afghanistan's security situation has deteriorated significantly in recent weeks, with a spate of political killings, violent protests, and attacks on humanitarian workers, US-based Human Rights Watch said.

The recent violence includes the assassination of a parliamentary candidate in Ghazni two weeks ago, the murder of three female aid workers, and clashes between armed factions in the northern province of Maimana.

In the Afghan capital, Ms Cantoni's colleagues launched a poster campaign today to appeal for her release, which was distributed around the city by aid workers and Afghan widows who had been helped by Cantoni's projects.

The posters include a picture and the text "Please help Clementina. She has been taken. For three years she served 10,000 widows and 50,000 war orphans in Afghanistan".