A group of Royal Marines has been involved in a firefight in Afghanistan in which two suspected enemy fighters are believed to have been killed.

The battle happened at about 0600 BST (0500 local time) on Thursday, near Khost in the troubled Paktia region of south-eastern Afghanistan.

At least two people were hit... we don't know whether they were dead or alive

Lieutenant Colonel Ben Curry

Defence spokesmen said it was the first time marines have fired a shot in anger in Afghanistan.

Marines spokesman Lieutenant Colonel Ben Curry said the incident began with an attack on 12 reconnaissance troops manning a "covert" observation post.

A car carrying three gunmen pulled up about 200 metres away, firing about 10 bullets at the marines.

"We fired back in self-defence. At least two people were hit."

He said a second vehicle drove up some time later and two bodies were seen being taken away.

"But we don't know whether they were dead or alive," he said.

No marines were injured in the incident. The third gunman was thought to have driven away in the first car.

The marines did not attempt to stop the second car. Two French coalition jets were sent to track it, but were unable to establish where it went.

Local feuds

Defence chiefs, who have begun an investigation, have not confirmed whether the gunmen were believed to be Taleban or al-Qaeda fighters, or someone entirely different.

Lieutenant Colonel Curry later told BBC News it would be "irresponsible" to speculate thus far on who the attackers were - or why they targeted the marines.

Lieutenant Curry: Attackers got "more than they bargained for"

"I'm not 100% sure why they were attacked. Perhaps they were spotted beforehand and this was some form of deliberate attack.

"If it was it was a rather poor one... clearly the people who engaged the patrol were not 100% sure what they were firing at, and I'm afraid to say they got rather more than they bargained for."

Correspondents in the area said it was possible the marines had somehow been caught up in a local dispute.

Lieutenant Colonel Curry added: "Afghanistan is a dangerous place. There are not only the al-Qaeda and Taleban operating in the area, but also there are warlords who are fighting their own tribal problems."

An investigation is also being conducted to determine how the patrol's cover was blown.

The reconnaissance force has since been returned from the "compromised" post, to be debriefed at the main marines base in Bagram.

Condor ends

It is not the first time marines have come under fire in Afghanistan.

On Wednesday two rockets were fired at a base housing about 50 marines just south of Gardez - but missed by about one kilometre.

It's unclear what enemy are there... everybody's got weapons

Major Phil Joyce

Also on Wednesday the marines ended Operation Condor, their search for al-Qaeda and Taleban fugitives in eastern Afghanistan, without making contact with the enemy.

Major Phil Joyce, one of the 800 or so UK marines involved in the operation, spoke of the difficulty of identifying the enemy in a region where every village had its own security force and defence weaponry.

"Certainly it's not a clear-cut battlefield. Any al-Qaeda are likely in the middle of the villages, mixed with the residents.

"You have to separate the insurgent from the resident. It's unclear what enemy are there... everybody's got weapons."