Washington, Jan 1 :US President Barack Obama offered his condolences Thursday after seven employees of the Central Intelligence Agency (CIA) were killed and six injured in a suicide attack Wednesday on a military base in eastern Afghanistan.

In a letter to CIA employees, Obama called those killed "brave Americans (who) were part of a long line of patriots who have made great sacrifices for their fellow citizens, and for our way of life".

The Wednesday evening bombing, killing at least eight people, marks the worst one-day loss of life for the CIA since the bombing of the US embassy in Beirut in 1983, according to US media.

Obama paid tribute to the CIA: "You have helped us understand the world as it is, and taken great risks to protect our country."

Afghanistan's former ruling Taliban claimed responsibility for the bombing at Forward Operating Base Chapman in Khost province near the Pakistan border. A Taliban spokesman said it was carried out by an Afghan soldier.

CIA Director Leon Panetta, in a memo to employees, said "those who fell were far from home and close to the enemy, doing the hard work that must be done to protect our country from terrorism". (DPA)