The NATO alliance said two of its troops have been killed in southern Afghanistan.

NATO said the soldiers were killed Tuesday, but it did not give their nationalities or provide other details.

In another statement Tuesday, NATO said Afghan forces supported by the alliance have killed one insurgent and arrested three others suspected of involvement in this month's deadly suicide bombing near the German embassy in the capital, Kabul.

The Taliban claimed responsibility for the January 17 attack, which killed four Afghan civilians and a U.S. soldier on a road between the embassy and a U.S. military base.

The operations to capture the suspects were carried out in Kabul and Logar province, south of the capital city.

Military officials said about 3,000 more U.S. troops have taken up positions in Logar province and the neighboring province of Wardak.

Afghanistan has seen a surge in violence over the past year, as Taliban fighters stepped up attacks aimed at undermining the U.S.-backed government of President Hamid Karzai.

The United States has about 30,000 troops in Afghanistan, and U.S. President Barack Obama is expected to authorize plans to send up to 30,000 more to try to reverse the growing instability. 

Some information for this report was provided by AFP, AP and Reuters.