A senior government official on Monday rejected a call from Pakistan opposition leader Benazir Bhutto for foreign experts to help investigate the suicide attack on her homecoming procession from overseas exile.

Bhutto said Sunday she wanted U.S. and British experts to assist in the probe into the Thursday night bombing in Karachi that killed 136 people, wounded hundreds more, and raised the question of whether campaign rallies would be allowed ahead of upcoming parliamentary elections.

But Interior Minister Aftab Khan Sherpao said foreign experts would not be brought in for the investigation.

"I would categorically reject this," he told reporters. "We are conducting the investigation in a very objective manner."

Bhutto, who escaped the blast because she had stepped into her armored bus minutes before the bomb went off, has called for an independent inquiry, questioning why many streetlights were not working as her convoy inched its way through the darkness, and noting the chief investigator is a police officer who had been present when her husband was allegedly tortured while in custody on corruption charges in 1999.

"The inquiry should be led by Pakistan, but the government should call on foreign experts so that the killers ... can be brought to justice without any doubts," she told reporters Monday at the Karachi tomb of Pakistan's founding father, Mohammed Ali Jinnah. Her convoy had been heading to the tomb when the bombs went off Thursday.

President Gen. Pervez Musharraf has promised to conduct a thorough probe. Police are questioning three people but have yet to announce any breakthroughs.

Violence has long accompanied Pakistan's murky politics, as have bitter political feuds and ripping conspiracy theories.

On Monday, the head of the ruling party reacted to Bhutto's accusations of possible government involvement in the attack by saying he could also raise the prospect of intrigue -- and promptly accused Bhutto's husband of being behind the attack.

"We will also say all this was a conspiracy," Chaudhry Shujaat Hussain said on Geo television, saying Bhutto's husband, Asif Ali Zardari, had plotted the attack with party leaders to raise sympathy for her.

Zardari "hatched a conspiracy and they implemented it," Hussain said, noting Bhutto had gone into the bus just before the explosions.

Hussain offered no evidence to back that up and appeared to be responding to barbs aimed at the conservative wing of the ruling party, which could be sidelined if Bhutto triumphs in January elections.

Bhutto was quick to respond.

"The president of the PML-Q is protecting the killers and says the Peoples Party was behind the blast. That's why I said foreign assistance in the Pakistan-led inquiry is very necessary," she said.

The government has already rejected Bhutto's allegation that elements within the administration and security apparatus were trying to kill her.

She claims they are remnants of the regime of former military leader Gen. Zia-ul Haq, who oversaw the creation of mujahedeen groups that fought the Soviet occupation of Afghanistan. Veterans of that fight later formed al-Qaida and the Taliban.

Haq's son, now Musharraf's religious affairs minister, has suggested that Bhutto was responsible for the carnage by not heeding warnings that she would be targeted.

Pro-Taliban Islamists and a popular former prime minister, meanwhile, on Monday condemned a ban on campaign rallies proposed after the suicide bombing, calling it an attempt to rig elections.

Sadiq ul-Farooq, a leader of former Prime Minister Nawaz Sharif's Pakistan Muslim League-N party, claimed the proposal would prevent "popular opposition leaders from reaching their voters."

Sherpao said the proposal would allow gatherings in specific, well-protected areas, but would ban large processions and rallies. Further violence, he indicated, could lead to a rescheduling of the vote.

"We do not want to postpone the elections and we do not want any sort of any excuse for that," he said. "We want a peaceful, conducive atmosphere."

There are growing signs that Musharraf and Bhutto are moving toward an alliance with a common mission to fight Islamic extremism, despite their longtime enmity.

That would leave Sharif, who was ousted when Musharraf seized power in a 1999 coup, to lead an opposition likely to include religious parties bitterly opposed to Pakistan's front-line role in the U.S.-led war on terror.

Ameer ul-Azeem, spokesman for the Mutahida Majlis-e-Amal, a coalition of opposition religious parties, denounced Musharraf as a "dictator who calls himself a democrat."

"Since Musharraf knows the ruling party is not able to organize any big rallies, he is now thinking of depriving opposition parties of their right to campaign," ul-Azeem told The AP.

While authorities allowed Bhutto to return, Sharif was immediately deported when he flew into Pakistan on Sept. 10 from exile on a self-declared mission to force Musharraf from power.

Ul-Farooq insisted Sharif would try to return again within the next month. Sharif served two terms as prime minister in the 1990s and remains Pakistan's most popular politician, according to a recent poll.

Musharraf has pledged to quit his position as army chief and restore civilian rule if he secures another five-year presidential mandate.