A plan for US President George W. Bush to visit Pakistan on Saturday remains in place, in spite of the death of a US foreign service officer – one of at least four people killed – in Thursday’s suspected suicide car bomb attacks in Karachi.

Two car bombs exploded near the US consulate building in Pakistan’s southern business city, less than 48 hours before Mr Bush was due to visit the country, a key ally in the US-led war on terrorism. The explosions injured at least 40 people.

In New Delhi, Mr Bush told reporters he was determined to travel to Pakistan. “I’ve been briefed on the bombings. We have lost at least one US citizen in the bombing, a foreign service officer . . . Terrorists and killers are not going to prevent me from going to Pakistan.”

The American was killed in the attack along with his driver and a Pakistani paramilitary trooper. A fourth body has not been identified, but police suspect it to be that of a suicide bomber. Smoke could be seen from locations across Karachi’s business centre, and several cars were on fire near the parking lot of Karachi’s Marriott hotel adjacent to the US consulate building.

“This is a message from the hardliners and militants. They are saying, in spite of claims by [military ruler Gen Pervez] Musharraf that he’s succeeding, ‘We are around and active’,” said Hasan Askari Rizvi, a commentator on defence and security affairs. “With this single attack the pretence of security conditions improving in Pakistan has been demolished.”

Fawzia Wahab, a member of parliament belonging to the opposition Pakistan People’s party [PPP], said: “This attack . . . tells people our country is very volatile, highly militarised and just not stable.”

No one immediately accepted responsibility for the explosion. But police and senior government officials said the attack bore the hallmarks of al-Qaeda, possibly in association with one of its local affiliate groups.

“The timing of this attack is critical. It comes ahead of Mr Bush’s visit. That in itself is telling evidence of intentions behind it,” said a Karachi police official, who asked not to be named.

In Islamabad, a senior government official said: “Only al-Qaeda has the means and the reason to back such an attack at this time.” He said the use of suicide attacks was an increasingly common al-Qaeda tactic in Iraq and Afghanistan.

Investigators were also looking into the possibility the attack could be linked to Jundullah – a shadowy militant group backed by al- Qaeda, which had 11 members sentenced to death by a Pakistani court last week for their involvement in a 2004 attack on General Ahsan Saleem Hayat, Karachi’s former military commander.

Gen Hayat is now the vice-chief of army staff – the second highest ranking military position after Gen Musharraf.

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