Al-Jazeera, based in Qatar, called on the British government to confirm or deny the report, which appeared Tuesday in the Daily Mirror, a London tabloid.

The network has been a frequent target of U.S. criticism, and its facilities have been hit by U.S. bombs in Afghanistan and Iraq. Al-Jazeera said the Daily Mirror report would be "both shocking and worrisome" if true.

"It would cast serious doubts in regard to the U.S. administration's version of previous incidents involving Al-Jazeera's journalists and offices," the network said in a statement. "It would also constitute a new chapter in the relationship between two of the most powerful governments in the world and media organizations in general," the statement said.

The Daily Mirror reported that Blair talked Bush out of launching an airstrike against Al-Jazeera's headquarters in Qatar - a U.S. ally - during an April 16, 2004, meeting at the White House.