The premier also told the house he would announce on Tuesday a multi-party parliamentary commission to oversee the implementation of the landmark 18th Amendment, whose unanimous passage by both houses of parliament last month restored a genuine parliamentary democracy in the country.

Opposition leader Chaudhry Nisar Ali Khan found fault with almost everything the government was doing — such as celebrating the passage of the Constitution (Eighteenth Amendment) Bill, its moves after the release of a UN inquiry report about Ms Bhutto's Dec 27, 2007 assassination, its handling of power shortages and oil and gas pricing, a new labour policy announced on Saturday, a proposed new accountability law and recent talks with India — in a tirade that apparently angered the prime minister.

“We seriously differ with this style of governance,” the opposition leader said before leading the walkout mainly by his PML-N party, which was joined by most members of the rival PML-Q, just before the prime minister rose to reply to him.

Some opposition members later returned to the house, including PML-N chief whip Sheikh Aftab Ahmed, to hear Mr Gilani, but Chaudhry Nisar did not, prompting the prime minister's adviser on political affairs Nawabzada Ghazanfar Gul to accuse him later of violating “democratic etiquette and traditions” by failing to face a reply to his charges.

“Whoever is responsible for this will not be able to escape,” the prime minister said about the government's own inquiries following the UN report and added “Her blood will not be allowed to go waste.”

Mr Gilani cited the parliamentary unanimity in passing the 18th Amendment, a national consensus in the war against terrorism, and a 'right direction' given to the economy among major internal achievements of the two years of his government and said his recent participation in a US-hosted nuclear security summit had earned legitimacy for Pakistan's nuclear programme and his meeting with Indian Prime Minister Manmohan Singh in Bhutan last week had paved the way for resuming suspended peace talks with India.

He ridiculed the 'negative thinking' of those questioning the benefit of the 18th Amendment to the common people and remarked “Then some can also say 'what is the use of this parliament'.”

He assured the house to get the historic amendments implemented and said “I will announce the implementation commission tomorrow.”

Parliamentary sources said the commission would comprise nine members to be headed by PPP's Senator Raza Rabbani.