Eight Americans, reportedly working for the CIA, have been killed in a suicide bombing at a U.S. military base in eastern Afghanistan, local media reported on Thursday.

The attack occurred in Afghanistan's Khost province on Wednesday. U.S. media quoted unnamed officials as saying said the eight killed were working for the Central Intelligence Agency.

Neither the CIA, nor ISAF officials have commented on the incident.

Another blast hit on Wednesday the southern Afghan province of Kandahar, killing four Canadian soldiers and a journalist. Calgary Herald reporter Michelle Lang, 34, was traveling with a provincial reconstruction team to Kandahar city when their armored vehicle hit an explosive device.

The Khost province borders Pakistan's North Waziristan tribal region, where Taliban militants frequently stage cross-border attacks.

The NATO-led International Security Assistance Force (ISAF) and a separate U.S.-led coalition, involved in Operation Enduring Freedom, have more than 110,000 troops in Afghanistan. The United States has by far the largest force, with over 70,000 troops.

This year has been the deadliest for foreign troops in Afghanistan since radical Islamic Taliban group was toppled in a 2001 U.S.-led campaign. The independent iCasualties.org website, which tracks the numbers of foreign service personnel killed in Iraq and Afghanistan, says 520 have died in 2009.

KABUL, December 31 (RIA Novosti)