ISLAMABAD - A British police inquiry that concluded Pakistani opposition leader Benazir Bhutto died because of a bomb blast, not gunfire, is inadequate, a leading Pakistani rights group said.

"The Scotland Yard findings do not satisfy the basic requirements of any investigation,'' Asma Jehangir, head of the independent Human Rights Commission of Pakistan, said in a statement released late Saturday.

A British police report released Friday, after a 2�-week probe into the cause of Bhutto's death, said she died when her head struck the escape hatch of her armoured sports utility vehicle after a suicide attacker struck during a campaign rally on Dec. 27.

That finding supported a similar account from the Pakistani government. However, Bhutto's party rejected it, insisting she died of bullet wounds.

Jehangir noted Scotland Yard's report contradicted statements by people who were in Bhutto's vehicle, who said the explosion took place after Bhutto had slumped back into her seat.

In the absence of an autopsy and a thorough forensic examination of the crime scene, the police findings "can only be viewed as a hunch,'' she said.

President Pervez Musharraf said the government asked Scotland Yard to help in the investigation in order to quash speculation that government agents might have been involved in Bhutto's killing.

However, Bhutto's party said the British probe was too limited, and did nothing to clear up who was behind the attack.

Authorities have said they suspect Islamic militants based near the border with Afghanistan.

Jehangir said an independent investigation into Bhutto's killing cannot be held "under the shadows of the present authorities.'' She backed a call from Bhutto's party for a United Nations-led investigation -- something the government has ruled out.