KABUL, Afghanistan - Two foreign contractors helping the United Nations prepare for landmark elections and their Afghan driver were killed in an attack in a remote eastern province, senior Afghan officials said today.

The foreigners killed in Tuesday's attack were employees of Global Risk Strategies, a London-based security firm, said Farooq Wardak, the Afghan government's top election official. He didn't have the men's names or nationalities.

"I confirm that there was an attack by a number of people and two foreigners and one Afghan were killed," Deputy Interior Minister Hilalludin Hilal told The Associated Press.

Officials at Global Risk in London and Kabul had no immediate comment. A U.N. spokesman also declined to comment.

The company is surveying parts of rural Afghanistan as part of U.N. plans to register voters for September elections.

The Nuristan team "had already visited two districts and it was the third district that they wanted to survey," Hilal said.

The United Nations is pressing ahead with plans to register 10 million Afghan voters across the country, despite a surge in violence by Taliban-led militants.

The world body has already registered almost 2 million Afghans in eight major cities for the election, but only began on Saturday to sign up voters in the lawless countryside.

The world body has warned that the vote will fail if security is not improved, and has already had to suspend or delay registration work in the south and east of the country in response to several attacks.

Nuristan is one of four troubled provinces along the Pakistani border where registration was delayed because of poor security, Wardak said last week.

Wardak said today that he hoped that registration could still begin as planned on Thursday, probably without any U.N. international staff.

Still, no date has been set for registration to begin in Zabul, Uruzgan and Paktika - the other areas viewed as too dangerous for election work.

Last month, a roadside bomb was detonated by remote control in southern Kandahar as U.N. workers passed, forcing a suspension of all U.N. work in the region.

In March, U.N. officials were attacked with rocket-propelled grenades and gunfire as they slept in a government compound in southeastern Paktia province.

Slow registration already forced U.S.-backed President Hamid Karzai, the favorite to win the election, to postpone the vote from June to September.