Michael Howard, the Home Secretary, was about to wind up the debate at 6.40pm when he was told about the attack in a note from his officials. Intelligence services, led by MI5, are believed to have been expecting an attack.
Security around Westminster has been stepped up since the failure by Sinn Fein to accept the peace deal in the Downing Street declaration. Mr Howard said he was very concerned about the breach of security at Heathrow. 'We have been improving the operations that we have been putting into place to counter the terrorist threat, but we have always known that it is impossible to have any kind of guarantee that we would be able to stop and thwart all their evil deeds,' he said. 'I am very concerned about this attack and I will be getting reports.'
The Anglo-Irish talks in London today will go ahead in spite of the bombing, Downing Street confirmed. Sir Patrick Mayhew, the Secretary of State for Northern Ireland will meet Irish ministers to discuss further progress on the Downing Street declaration. Ministers will reaffirm their determination to press ahead with the political peace process in the absence of a response by Sinn Fein.
A Dublin source said: 'What happened tonight makes it more vital than ever to build on what the Downing Street declaration achieved. We will not be thrown off course in the joint bid for peace by this incident.'
The Home Secretary told the Commons of the attack minutes before it voted to renew the Prevention of Terrorism Act by 328 votes to 242 - a majority of 86. Mr Howard urged MPs to give their riposte to the IRA by continuing the powers, introduced under Labour in 1974 after the Birmingham pub bombings.
Liberal Democrat and Ulster Unionist MPs voted with the Tories, but Labour - after the row over the leaked talks between John Smith and John Major - voted against the powers. Labour had sought a return to the bipartisan approach, which ended a decade ago, by removing from the PTA the right to detain suspects without charge for seven days and powers to exclude alleged terrorists from the mainland of Britain.
In an acrimonious debate, Mr Howard warned Labour the police believed the powers were necessary. But Tony Blair, the shadow Home Secretary, calling for an independent review, said the powers breached civil liberties.
Mr Howard used the mortar attack to criticise Labour for opposing the PTA. 'If it was meant to send a signal to the House of Commons, it's a pity that the House was unable to give a united response. But the majority in favour of the renewal of the powers was a big majority. So if this was a signal from the terrorists, they got their answer from the Commons,' he said on Channel 4 minutes after the vote.
Mr Howard also assured Labour MPs that neither himself nor his aides were the source of the leak of the secret talks between the Labour leader and the Prime Minister.
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