Supporters of former Pakistan prime minister Benazir Bhutto insisted today that a UN inquiry was the only way to reveal the truth behind her murder.
They dismissed a government announcement that Scotland Yard anti-terror officers would help in the investigation.
Opposition parties also criticised the government's decision to delay parliamentary elections until February 18th - a six-week delay prompted by the rioting that followed Ms Bhutto's death.
A spokesman for the Pakistan People's Party
But they said they still plan to take part in the elections, seen as a key step in bringing democracy to Pakistan after years of military rule.
"The regime has lost all credibility. Neither a domestic inquiry nor vague foreign involvement . . . would lay to rest the lingering doubts and suspicions," said a spokesman for Ms Bhutto's Pakistan Peoples Party.
President Pervez Musharraf announced yesterday that police officers from London will help investigate the assassination. The government initially said it did not need foreign help to investigate the killing, and his reversal could ease pressure for an independent, international investigation into both how she died and whether the government covered it up.
Ms Bhutto's death in a gun and suicide bomb attack on December 27th plunged Pakistan deeper into crisis and stoked fears of political meltdown as the key US ally struggled to contain an explosion of Islamic militant violence.
The government declared just one day after the attack on Ms Bhutto that an al-Qaeda-linked militant orchestrated the killing and aired video footage. But the hasty accusation only cast doubt over the government's account of how she died.
Mr Musharraf blamed "terrorists" for the death of Ms Bhutto, a two-time prime minister and appealed for public unity to combat them.