The Army has released pictures of the grey Toyota Corolla that was used by militants who yesterday stormed the mosque frequented by serving and retired military personnel.
The Army asked persons having information about the vehicle to contact it on a specified phone number.
The car was found parked some distance from the mosque targeted by the terrorists.
The registration number of the car actually belonged to a vehicle in Islamabad, officials said.
Seven grenades, two national identity cards and several handwritten and typed documents were found in the car, media reports said.
Investigators are using these materials to trace the masterminds of the attack, officials said.
The probe is being conducted jointly by police in Rawalpindi and other security and intelligence agencies, including the Inter-Services Intelligence agency.
Police also registered an FIR at RA Bazar police station against "unknown terrorists". Two attackers blew themselves up in the mosque while two more were gunned down by security forces.
Maj Gen Umer Bilal, Director General of the Army's Armoured Corps, and four senior serving officers were among the 40 people killed in the assault.
Former Army vice chief Lt Gen Muhammad Yusuf was among the 83 people injured.
The suicide bombers used jackets packed with eight kg of explosives, ball bearings and other metal pieces.
A team of forensic experts and sleuths visited the site again today to look for clues.
Body parts of the bombers and other clues were gathered by officials yesterday.
Chief military spokesman Maj Gen Athar Abbas told reporters that authorities would ascertain if the attack was the outcome of a "serious breach" of security.
The mosque is located in a sensitive area near the Army's General Headquarters where a large number of serving and retired military personnel live.
The attack caused concern in the military establishment as security in the area was beefed up after a group of militants tried to storm the General Headquarters in October.
Islamabad: Investigators probing the terror attack on a mosque that killed 40 people, including a major general, in Pakistan's garrison city of Rawalpindi, have zeroed in on a car used by the assailants to trace the masterminds of the assault.
First Published: Saturday, December 05, 2009, 15:57