LAHORE: Raymond Davis, a CIA contractor, charged with double murder after shooting dead two men in Lahore refused to sign a charge sheet in court Friday and insisted he had diplomatic immunity, lawyers said.

The hearing in the murder case against Davis took place amid high security in Kot Lakphat jail in Lahore where he is being held, and was adjourned until March 3.

“Davis refused to sign the copy insisting that he be released and claiming that he enjoys immunity,” public prosecutor Abdul Samad told AFP.

Samad said that Davis, who claimed he acted in self-defence when he shot the men in a busy Lahore street last month, was handcuffed during the hearing which was guarded by more than 300 armed police officers in and around the prison.

A separate legal process to determine the diplomatic immunity issues returns to the Lahore High Court on March 14.

Revelations that Davis was a CIA contractor have heaped pressure on Pakistan's government and further ramped up burning public mistrust of Washington.

A third Pakistani was struck down and killed by a US diplomatic vehicle that came to Davis's assistance. US officials denied Pakistan access to the vehicle and the occupants are widely believed to have left the country.

Police have said they recovered a Glock pistol, four loaded magazines, a GPS navigation system and a small telescope from Davis' car after the January 27 shooting.

US Consul General Carmela Conroy and other American officials were present at Friday's hearing.

Asad Manzoor Butt, lawyer for the families of the men who were shot dead, rejected the American's immunity claim.

“We have also received copies of the charge sheet. We will pursue this case as we want Davis to be punished for his act. We believe he does not enjoy immunity,” he said.

Samad has said that the immunity case before the Lahore High Court would not affect the murder charge hearings, unless the higher court barred them from proceeding.

Washington is pushing hard for Pakistan to free Davis, arguing that he has immunity and backing his claim that he acted in self-defence.

The United States postponed a round of high-level talks with Afghanistan and Pakistan following failed attempts to get Davis out, and US lawmakers threatened to cut payments to Pakistan unless he is freed.