In Afghanistan, a bomb attack has killed two female election workers, and wounded at least 12 others. The violence comes only days before a NATO summit in Turkey considers Afghan President Hamid Karzai's request for increased security for upcoming national elections.

Witnesses and Afghan police say an explosion Saturday ripped through a minibus carrying mostly female U.N. election workers in the eastern town of Jalalabad. At a news conference in Kabul, a spokesman for the U.S.-led military coalition, Lt. Col. Tucker Mansager, described the deadly incident.

"Apparently, there was an improvised explosive device that detonated near a joint electoral management vehicle in the vicinity of Jalalabad," he said.

Islamic militants linked to Afghanistan's ousted Taleban government have claimed responsibility for the attack, saying it was meant to disrupt the election process.

A Taleban spokesman threatened all those who take part in the scheduled elections, both voters and those working to register them. He said the election process strengthens the foundations of the U.S.-backed government, which the Taleban opposes.

The Taleban spokesman also claimed responsibility for Thursday's killing of two U.S. soldiers in an ambush in Asadabad, the capital city of eastern Kunar province.

Coalition spokesman Mansager says no one has yet been arrested in connection with that attack.

"The contact occurred about 58 kilometers northeast of Asadabad. It was a direct contact between anti-coalition militants and our forces up in that area,"said Lt. Col. Tucker Mansager. "There is no one detained."

The violence comes only days before NATO convenes in Turkey to consider Afghan President Hamid Karzai's request for increased security to protect the national elections in September.

NATO's top military commanders have said they are confident that NATO will meet its commitments to Mr. Karzai's transitional government, which is seeking to extend the central government's influence throughout the country.

Speaking to reporters in Kabul Saturday, a spokesman for the NATO-led peacekeeping forces, Chris Henderson, said that violence, opium production, terrorism and issues of governance facing Afghanistan will come under discussion during the two-day NATO summit starting in Istanbul on Monday.

"There are enormous expectations that the international community will continue to invest in Afghanistan's future, and NATO will play an increasing role in that future," he said.

Nearly 6,500 NATO troops are confined mainly to the Afghan capital, Kabul. A small contingent of German forces is stationed in the northern province of Kunduz.

NATO has promised to expand to other northern towns in time for the elections in Afghanistan, but member states have been reluctant to offer extra troops and equipment.