WASHINGTON: Raymond Davis, the American held in Pakistan on double murder charges for a shooting in Lahore last month, is employed by the CIA as a contractor, U.S. sources closely following the case said on Monday.

Davis, who is being held in a Lahore jail amid a diplomatic dispute over whether he has diplomatic immunity, was working as a "protective officer," the sources said.

U.S. officials who declined to be identified told Reuters Davis' duties as a protective officer -- essentially a bodyguard, were to provide physical security to U.S. Embassy and consular officers, as well as visiting American dignitaries.

The officials strongly denied news reports alleging Davis was part of a covert CIA-led team of operatives conducting surveillance on militant groups in Pakistan. The officials insisted Davis was not part of any undercover operations team.

Two U.S. sources familiar with the matter confirmed to Reuters that Davis, a former member of the U.S. Special Forces, had previously worked on contract as a security officer for Xe Services, a controversial private contractor formerly known as Blackwater.

Confirmation of a connection between the jailed American and the U.S. Central Intelligence Agency came as President Barack Obama's administration sought to step up pressure on authorities in Pakistan to improve security for Davis.

The shooting has caused outrage in Pakistan, whose help Washington relies upon to quash militants. There have been media reports citing a connection with the CIA.

Davis has been held by authorities in Lahore since last month on charges of murdering two men who Davis says were trying to rob him.

A U.S. source who has been following the case closely said Monday Washington is greatly concerned that Davis, for whom the U.S. government has been claiming diplomatic immunity, is facing enormous risks to his life in the jail where he is being held. AGENCIES