The main suspects in the assassination are the foreign and Pakistani Islamist militants who saw Ms Bhutto as a Westernised heretic and an American stooge, and had repeatedly threatened to kill her.

But fingers will also be pointed at the Inter-Services Intelligence agency, (ISI) which has had close ties to the Islamists since the 1970s and has been used by successive Pakistani leaders to suppress political opposition. Ms Bhutto narrowly escaped an assassination attempt in October, when a suicide bomber struck at a rally in Karachi to welcome her back from exile.

Earlier that month two Pakistani militant warlords based in the country’s northwestern areas had threatened to kill her.

One was Baitullah Mehsud, a top militant commander fighting the Pakistani Army in South Waziristan, who has ties to al-Qaeda and the Afghan Taleban. The other was Haji Omar, the leader of the Pakistani Taleban, who is also from South Waziristan and fought with the Afghan Mujahidin against the Soviets in Afghanistan.

Ms Bhutto said after the attack that she had received a letter, signed by someone claiming to be a friend of al-Qaeda and Osama bin Laden, threatening to slaughter her like a goat. But she also accused Pakistani authorities of not providing her with sufficient security, and hinted that they may have been complicit in the Karachi attack.

She indicated that she had more to fear from unidentified members of a power structure that she described as allies of the “forces of militancy”.

Analysts say that President Musharraf is unlikely to have ordered her assassination, but that elements of the Army and intelligence service stood to lose money and power if she became prime minister. The ISI includes some Islamists who became radicalised while running the American-funded campaign against the Soviets in Afghanistan and were opposed to her on principle. Saudi Arabia is also thought to have frowned on Ms Bhutto as being too secular and Westernised and to have favoured Nawaz Sharif, another former Prime Minister.

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