A new chief investigator has been appointed to probe the suicide attack on opposition leader Benazir Bhutto, after she claimed the previous officer was complicit in the torture of her husband in 1999, an official said Thursday.

Saud Mirza, the chief of criminal investigations at Karachi, will now head the five-man team probing last week's bombing of Bhutto's homecoming parade that killed 136 people, said Ghulam Muhammad Mohtarem, the home secretary of Sindh province.

"There is no other change in the team," Mohtarem said.

The Sindh police chief replaced the previous chief investigator, Manzar Mughal, after Bhutto, back from eight years in exile, claimed Mughal had been present while her husband, Asif Ali Zardari, was tortured in custody on corruption charges in 1999.

Bhutto, who escaped injury in the bombing, has blamed Islamic militants for the attack on her, but has also accused elements in the government and the security services of complicity, demanding international experts be called in to help in the investigation — a call rejected by the government.

The new appointment changes nothing and the inquiry remains inadequate, said Farhutallah Babar, a spokesman for Bhutto's Pakistan Peoples Party.

"Our concerns were the inquiry should be conducted by international experts and that has not happened. The more it gets delayed the more the crucial evidence will be lost," he said.

On Wednesday, a statement from the party dubbed the present inquiry as "inept," citing a lack of arrests of suspects and confusion over the cause of the blast.

Authorities say it was likely carried out by two suicide bombers, and have released a picture showing the head of one of the bombers but have yet to identify him.

The attack has raised fears about Pakistan's stability amid a rising Islamic militancy — fears underlined Wednesday when the government announced it had sent 2,500 troops into the Swat valley in northwestern Pakistan to combat a militant cleric who calls for Taliban-style rule and holy war against Pakistani authorities.

But the attempt at intimidation appeared to fall flat, as some 6,000 supporters of the cleric, Maulana Fazlullah, gathered in a schoolyard to hear him speak just a few kilometers (miles) from where the soldiers deployed.