SPIN BOLDAK, Afghanistan (Reuters) - Taliban guerrillas claimed responsibility Tuesday for the weekend killing of a French aid worker that has prompted the U.N. refugee agency to withdraw staff from the south and east of Afghanistan.

The attack Sunday that killed 29-year-old U.N. refugee agency official Bettina Goislard raised pressure on the international community to send peacekeeping troops to provinces where resurgent Islamic militants and warlords hold sway.

Referring to the killing in the town of Ghazni, southwest of Kabul, Taliban spokesman Mullah Abdul Samad told Reuters:

"Yes, we did that. Our guerrillas were involved in killing that Christian woman. We have confirmed information that most of the foreigners working in our country are American agents and have no sympathy for Afghanistan.

"We will not spare them," the Taliban spokesman said. "They are not doing anything for common Afghans, but are preaching Christianity in Afghanistan or spying against the Taliban."

Another Taliban spokesman denied the militia's involvement, but government officials, local residents and U.N. sources blame the Taliban for repeated attacks on "soft targets" such as aid workers.

UNHCR WITHDRAWAL

The U.N. High Commissioner for Refugees (UNHCR), Goislard's employer, said it was withdrawing 30 international staff from the east and south of Afghanistan and closing refugee reception centers in Nangarhar, Paktia, Khost and Kandahar provinces.

Aid officials in Kabul say the move, which mainly affects Afghan refugees in Pakistan wanting to return home, sent a clear signal to Pakistan to do more to clamp down on Islamic militants regrouping on its side of the border.

Goislard, shot in broad daylight by two men on a motorcycle, was the first U.N. international staff member killed since U.S.-led forces overthrew the Taliban two years ago.

She will be buried in Afghanistan in accordance with her wishes, the UNHCR said in a statement.

The killing of Goislard has raised the stakes in the Taliban's battle with the Western-backed government of President Hamid Karzai and the foreign presence in Afghanistan.

It also underlines the Taliban's ability to carry out attacks with impunity in large parts of the south and east.

WARNING FOR TURKISH CAPTIVE

The Taliban's deputy commander for southern Afghanistan warned Karzai's government it was ready to kill Turkish engineer Hassan Onal, kidnapped last month while working on a key road project in the south. Mullah Sabir, alias Momin, demanded the release of comrades in jail in Ghazni in return for Onal's freedom.

"But the Afghan administration is not showing any interest in his release. If the situation persists, we will be forced to kill him and his body will soon be found."

Momin added that anyone working in the interests of the United States was liable to be killed. "This includes journalists, NGO activists, drivers, engineers, and others."

South Korea, which has 200 troops serving in Afghanistan temporarily closed its embassy in Kabul after a warning that Osama bin Laden's al Qaeda network could launch a suicide bomb attack, state television said Tuesday.

Three South Korean diplomats have been evacuated to Pakistan, the television said.

The United Nations and Karzai have been calling for NATO-led international peacekeepers to be deployed in restive southern provinces, and Goislard's death reinforced those demands.

"When one of the U.N. agencies suggested that couldn't there be some expansion of ISAF into Ghazni, they were told that that was considered unsafe and they did not want to expand international military forces there," said William Byrd, World Bank country manager in Afghanistan.

"It is a bit odd that people are trying to deliver aid where even international military forces are not there in a peacekeeping mode," he told a signing ceremony in Kabul.

Momin said that on the orders of supreme leader Mullah Mohammad Omar, every day "hundreds" of Taliban members were returning to Afghanistan and were reaching the southern province of Zabul, which the guerrillas had made their headquarters.

More than 350 people have been killed in a wave of violence since August, much of it linked to the Taliban. Members of the al Qaeda network of Osama bin Laden are also thought to be attacking the 11,500-strong U.S.-led force in the country.