Slain former premier Benazir Bhutto's [Images] party on Wednesday said it had submitted a petition to the United Nations seeking an investigation into her assassination after the Pakistan government refused to forward the request to the world body.

The Pakistan People's Party simultaneously launched an initiative to lobby governments around the world to back its demand for a UN-led inquiry. A delegation led by Bhutto's security advisor Rehman Malik travelled to Norway to explain the need for an international investigation to trace those responsible for her killing.

"The PPP has a secretariat in New York through which the petition has been sent to the UN," PPP spokesman Farhatullah Babar told PTI.

"We will also approach governments around the world to explain our demand for the UN-led inquiry and to seek support for it," he said.

The government had earlier rejected the PPP's demand for a UN-led inquiry on the lines of the investigation into the killing of Lebanese prime minister Rafik Hariri, saying the world body's help could be sought only in matters involving two countries.

But PPP co-chairman Asif Ali Zardari had on Tuesday said the government's claim that Bhutto was murdered by operatives of Al Qaeda [Images] had lent weight to the party's demand for a probe by the UN.

"The regime itself has been calling it the handiwork of Al Qaeda, which is an international organisation with bases outside Pakistan. If that indeed is the case, there is all the more reason why the UN must be requested to investigate," Zardari told media persons.

He also said he discussed the need for a UN probe with experts like former UN Secretary General Kofi Annan and rights activist Asma Jehangir, who had supported the party's stance.

After Bhutto's assassination on December 27, the UN had said it will assist in the investigations if requested to do so by the Pakistan government.

Zardari also met Scotland Yard investigators probing Bhutto's assassination yesterday and handed over some materials to the British experts.

He was of the view that Pakistan's act of inviting a Scotland Yard team to look into his wife's murder was tantamount to admitting that any probe by domestic agencies was inadequate.