"I think whoever has to gain from her death, and definitely the sitting government has to gain from her death.

They should be held responsible...," Zardari, who was named the co-chairman of his Pakistan People's Party on Sunday, said.

He described as "too far-fetched" government's claims that the Taliban and al Qaeda were behind Bhutto's killing and called on US President George W Bush to ensure that an international investigation is carried out into the December 27 slaying of his wife.

"The government has been trying to put a new spin on it every day, but the latest piece of evidence that has come on the television is Channel 4 report of the exact way the assassin hit Benazir and the exact position and everything is now very clear that she was shot.

"I had maintained from the first day that she was shot either point blank or by a very high-powered sniper rifle. Now it seems that she was shot nearly point blank by a pistol," Zardari said, debunking the government's assertion that Bhutto died due an injury from the sun-roof lever of her car.

"It just proves they've just been trying to muddy the water from the first day," he said in a telephone interview with CNN.

Zardari was asked if he believed that Baitullaa Masud, the Taliban leader with suspected al Qaeda links was responsible for killing of Bhutto.

"... when the first attack took place, that is what the government claimed. And Benazir herself had denied that. On the second day she said I will not hold him or any of these so-called al Qaedas responsible. She left a letter for you also in which she does not put the responsibility on the al Qaedas," he said.

Zardari said his Pakistan People's Party had called for an investigation team under the auspices of the UN, the United Nations to be assisted by the British authorities.

"We are going to be writing to the United Nations and we are going to be writing to the British prime minister and British Parliament and we are hoping to lobby in America for their support, too," he said.

Asked if he believed that the government of the president, Pervez Musharraf, was directly responsible for ordering the killing of his wife, he said he will not take any position at the moment as he has asked for an international investigation but maintained that government had failed to provide her adequate security.

"I will wait for the international investigation to come and find out... We'd written so many letters to them. We'd written, asked for international assistance for security which they did not do. There are so many reasons that I should be apprehensive of the present government," Zardari said expressing doubts that the assassination could be the handiwork of the Taliban and the al Qaeda.

"It's not the question of they didn't like her, but it is too far-fetched. If we win, then we come, and then maybe they would have taken another approach to it."

Zardari pointed out that Masud had already denied any role in the killing.

"The whole situation of al Qaeda and the terrorists is very wishy-washy. We have too many things going around that seem to be pointing towards different sources in Pakistan,"

The PPP leader said asserting that it is "obviously" the government that benefits from the death of Bhutto.

"They all benefit because there is no alternate, there is no Benazir Bhutto, there is no larger than life figure to oppose them. Because she was not looking for just shared government to come into government, she was looking for them to go back, oust the army and get into power and get the people's government, like democracy going," he said.

Zardari was asked what he wanted the United States and Bush to do.