KABUL — The Taliban claimed responsibility today for two separate bomb attacks in Afghanistan that killed eight Americans, five Canadians and an Afghan in a surge of violence in the war-battered country. A U.S. congressional official said CIA employees were believed to be among the victims of a suicide blast at an American base in the volatile east.

The explosion at the Forward Operating Base Chapman base in Khost province on Wednesday killed eight American civilians and one Afghan, the worst loss of life for the U.S. in the country since October.

Separately, four Canadian soldiers and a journalist embedded in their unit were killed Wednesday by a roadside bomb in the southern Kandahar province, the bloodiest single incident suffered by that country's military in 2009.

Michelle Lang, a 34-year-old health reporter with the Calgary Herald, was the first Canadian journalist to die in Afghanistan. She arrived in the country just two weeks ago.

The Taliban claimed responsibility for both attacks in messages.