A US citizen has been shot dead by an Afghan employee in a baffling attack at an annex to the US embassy used by the CIA in Kabul, officials said yesterday.

The gunman was killed in the incident at the the Ariana Hotel compound late on Sunday and another US citizen was also wounded in the attack.

It was the latest eruption of violence to hit supposedly secure sites in Kabul after Afghan peace envoy Burhanuddin Rabbani was assassinated on September 20 and a 19-hour assault targeting the US embassy on September 13.

The attack comes as Washington steps up pressure on Islamabad to tackle the Haqqani network, a group linked to Al-Qaeda and loyal to the Taliban, blamed for much of the violence in Kabul and whose leaders are based in Pakistan.

“There was a shooting incident at an annex of the US embassy in Kabul involving an Afghan employee who was killed,” said US embassy spokesman Gavin Sundwall. “One US citizen was killed, one was wounded.”

Mr Sundwall said the Afghan employee had acted as “a lone gunman”.

Spokesman Zabihullah Mujahid said he was looking into what had happened.

The militia, which is leading a bloody, decade-long fight against Afghan government forces and the 140,000-strong foreign military, have used attackers with links inside the Afghan security forces to launch previous assaults.

Mr Sundwall said it was the first attack of its kind “within collective memory” although Afghan soldiers have killed their American military trainers.

On April 27, an Afghan ex-pilot opened fire after a row at a Kabul training centre, leaving eight US troops and an American contractor dead.

It was the worst attack of its kind and raised fresh questions over the massive US-led effort to expand and train Afghanistan’s military and police to take control of security when foreign combat operations end in 2014.