International aid workers kept a low profile Friday after the brazen daylight kidnapping of three foreign U.N. election staff in Kabul (search).

Investigators were searching for the three foreigners abducted from a marked U.N. vehicle around midday Thursday.

Police on Friday arrested seven suspects and cordoned off an area west of Kabul, Interior Ministry spokesman Latfullah Mashal said.

Three of the seven were armed men wearing military uniforms without belonging to any regular military or police unit, Mashal said, though interrogation of the suspects had established no link to Thursday's kidnapping.

Two of the victims were women, one with joint British-Irish nationality, and one from Kosovo. The third was a male diplomat from the Philippines. All work for a joint U.N.-Afghan commission overseeing landmark presidential elections.

The abductions come a week after a suicide attack killed an American woman and an Afghan teenager in the normally secure Afghan capital and ahead of final results due in the historic Oct. 9 poll.

U.S.-backed interim leader Hamid Karzai (search), who looks set to become the nation's first president-elect, condemned the abduction as "a criminal act ... against the Afghan people, aimed at derailing the process of peace and prosperity."

"Kidnapping won't be tolerated and every possible measure will be taken to ensure the security of the U.N. employees and other international organizations," he said in a statement.

A man claiming to speak for a Taliban splinter group, Jaish-al Muslimeen, said it was responsible for the kidnappings but offered no proof it was holding the three.

Staff of aid agencies were told to restrict all but essential movements around Kabul, which is patrolled by thousands of NATO peacekeepers, making it usually one of the safest places in the country.

"It's an ominous development," said Paul Barker of the aid group CARE (search) International. "We've not seen this kind of incident in Kabul before and I think we are still trying to figure out if it is a new trend or a one-off. Until it's resolved, we won't really know."

Afghan and NATO forces put up roadblocks around the city, and police and troops searched houses. The American military said it was ready to help in any rescue operation.

"We're still searching but we haven't been able to find them. We've got no leads," Interior Ministry spokesman Latfullah Mashal said Friday.

The three were abducted about a half mile from an election office in Kabul. Their Afghan driver, who was beaten and left behind, told investigators that about five armed men in uniform got out of a black four wheel drive vehicle that pulled in front of their U.N. vehicle. They forced the foreigners into their car and drove off.

In New York, U.N. Secretary-General Kofi Annan said the world body was hoping for the abductees' "immediate and unconditional release."

The Irish government identified one of the abductees as Annetta Flanigan.

The Philippines identified the abducted Filipino as Angelito Nayan, a foreign service officer who had joined the U.N. electoral effort.

Late Thursday, Ishaq Manzoor, who claimed to speak for the Taliban splinter group said it had staged the kidnapping and taken the three to a "safe place."

"We are checking their identities and we will demand that if their countries have forces in Afghanistan they should withdraw them," Manzoor told The Associated Press in Pakistan, speaking by satellite telephone.

About a half-dozen purported Taliban spokesmen call local and international media groups to make claims and take responsibility for attacks. Sometimes their claims prove false, and their links to the Taliban are impossible to verify.

Suspected Taliban rebels have kidnapped foreigners on several occasions during the past year in southern Afghanistan, but never in the capital.

In March, a Turkish engineer was shot dead and another abducted along the main Kabul-Kandahar highway. The survivor was released unharmed after three months.

About 1,000 people have died in political violence in Afghanistan this year, including more than 30 American soldiers. Still, it has not involved abductions or suicide attacks of the intensity seen in Iraq.