John McCain yesterday delivered a sharp rebuke to one of his most senior advisers who had suggested that another terrorist attack on America could propel the Republican nominee into the White House.

Charlie Black, a veteran Republican strategist who has already come under fire for his past ties to lobbyists, told Fortune magazine that a terror incident on US soil “certainly would be a big advantage” to Mr McCain.

He also cited the “unfortunate event” of the assassination of Benazir Bhutto in Pakistan in December, shortly before Mr McCain staged his comeback in the Republican primary contest. “His knowledge and ability to talk about it re-emphasised that this is the guy who’s ready to be Commander-in-Chief. And it helped us.”

The sudden row over his adviser embarrassed Mr McCain’s campaign yesterday, when he had hoped to focus on energy issues and a headline-catching initiative to offer $300 million (£150 million) to anyone who developed a revolutionary car battery.

Asked about Mr Black’s comments during a press conference in Fresno, California, Mr McCain stated that he wished to “strenuously disagree” with them. “I cannot imagine why he would say it. It’s not true,” he said. “I’ve worked tirelessly since 9/11 to prevent another attack on the United States of America. My record is very clear.”

Mr Black, confronted by reporters outside a fundraising event, read from handwritten notes. “I deeply regret the comments. They were inappropriate,” he said. “I recognise that John McCain has devoted his entire adult life to protecting his country and placing its security before every other consideration.”

Campaign officials said that he did not explicitly remember the comment, but did not dispute it. According to one source, he was trying to emphasise that Mr McCain was favoured by most voters on national security issues.

The campaign of the Democratic nominee, Barack Obama, seized upon the comments as further evidence of the type of politics that had been practised by the Republican in previous elections.

Bill Burton, a campaign spokesman, said: “Barack Obama welcomes a debate about terrorism with John McCain, who has fully supported the Bush policies that have taken our eye off of al-Qaeda, failed to bring Osama bin Laden to justice, and made us less safe. The fact that John McCain’s top adviser says that a terrorist attack on American soil would be a ‘big advantage’ for their political campaign is a complete disgrace.

“Barack Obama will turn the page on these failed policies and this cynical and divisive brand of politics so that we can unite this nation around a common purpose to finish the fight against al-Qaeda.”

Four years ago President Bush and other Republicans argued that his opponent, John Kerry, was soft on terrorism while questioning the record of the Democratic party record on national security after the 9/11 attacks. A tape from Osama bin Laden days before that election suggesting that he wanted Mr Kerry to win was widely regarded as having benefited Mr Bush.

Many measures taken by the Bush administration to protect the US, including the Guantanamo Bay camp for terror suspects and domestic wire tapping — as well as the war in Iraq — have become increasingly the focus of national or international controversy.

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