Hours after her jubilant return to Pakistan turned into tragedy when a huge explosive device was detonated close to her convoy, Bhutto claimed she had been targeted because she stood for democracy rather than extremism.

She claimed two suicide bombers were involved in the assault.

The presidential hopeful, looking sombre and wearing a black armband, told reporters in the garden of her relatives' Karachi home: "We will not stop our campaign, we will not stop our struggle. Despite the heavy losses we incurred yesterday, we will continue."

Bhutto demanded that the government launch an immediate inquiry into the attack, particularly into why street lights had been turned off shortly before it happened. She claimed that, had the street lights been on, her security personnel would have been able to see the attackers and intercept them.

But Bhutto also has questions to answer herself. She has so far failed to explain why she still insisted on setting off on a slow-moving, vulnerable convoy through Karachi's streets despite knowing from intelligence sources that at least four suicide cells were planning to attack her.

The wisdom of her decision appeared even more questionable after she revealed that 20 police officers and 50 young volunteer security guards drawn from her Pakistan's People's Party (PPP) were among the dead.

Bhutto maintained that those who died did so protecting what she termed her campaign for democracy. She said: "They stood their ground, and they stood all around the truck, and they refused to let the suicide bomber . . . the second suicide bomber . . . get near the truck."

Across a tense Karachi, funerals were held for the victims of the blast, which happened as Bhutto's convoy was making its way to a planned public rally. There were also calls for restraint.

At the city's Baitul Mukkaram mosque, high-profile cleric and Islamic scholar Taqi Usmani led Friday prayers, saying: "Save us from terrorism, from killings and from bomb blasts."

At the funeral of Inspector Shahab Khetian, a police veteran and the eldest of 10 brothers who was part of the security detail accompanying Bhutto, his nine-year-old son Zeeshan cried as the coffin was lowered into the ground. "Father don't go away, don't take my father away."

Once they have mourned the dead and dealt with the immediate aftermath of the attack, a key issue for Bhutto and her senior aides will be how best to spearhead the campaign for forthcoming parliamentary elections.

Claiming that the party also has information that attacks are being planned against her when she returns to her ancestral home of Larkana, the PPP will have to decide whether it can safely allow Bhutto to have anything other than a very restricted public profile. Such limited exposure could greatly hinder gaining further support for the PPP, which trades on the reputation of the former prime minister and her father, Zulfikar Ali Bhutto, who was hanged by a military regime in 1979.

Bhutto will undoubtedly seek to use the bombings to further burnish her self-portrayal as Pakistan's only chance of democracy. However, many people across the country have questioned her decision to enter a power-sharing arrangement with President General Pervez Musharraf . . . a deal that effectively opened the way for her to return to Pakistan after eight years of self-imposed exile.

She said of the deal: "We want to avoid bloodshed. We want to avoid loss of life. We believe democracy alone can save Pakistan from disintegration and a militant takeover. We are prepared to risk our lives and we are prepared to risk our liberty, but we are not prepared to surrender our great nation to the militants."

IN THE FRAME FOR THE KARACHI BOMBINGS AL-QAEDA

As the deadly enemies of the US and its ally, General Musharraf, it is inevitable that suspicion should fall on the network headed by Osama bin Laden, whose secret headquarters is in the tribal no man's land of south-western Pakistan, bordering Afghanistan.

Bhutto has won al-Qaeda's enmity by allying with Musharraf, enabling him to move smoothly from general to presidential candidate, and by becoming Washington's darling. She has also said she would allow American troops to fight on Pakistani soil . . .

something Musharraf has also permitted, though reluctantly and secretly.

TALIBAN The name of a Pakistani Taliban commander called Baitullah Mehsud was quickly mentioned among the chief suspects for the explosions, as he had threatened Bhutto with assassination earlier in the month. As a sworn enemy of "militants", who she says are trying to destroy Pakistan, and as a secular Muslim opposed to the introduction of shariah law, Bhutto is someone the fanatical Islamist militia who ruled Afghanistan until deposed by the United States in 2001 would be glad to be rid of. Mehsud said on Friday that he had "nothing to do" with the explosions in Karachi.

SECRET SERVICE

Bhutto's husband, Asif Ali Zardari, speaking from Dubai, was the first to suggest that the bombs could be the work of agents within Inter-Services Intelligence, Pakistan's military secret service.

This is not as far-fetched as it may sound, since two assassination attempts against General Musharraf have been carried out by elite forces that were supposedly committed to defending him.

Rogue elements of ISI have been and probably still are doing all in their power to help the Taliban.