The media's portrayal of Stephen Byers as a liar is false, according to Tony Blair.

Speaking publicly for the first time about the resignation of the besieged transport secretary, the prime minister attacked the media for its coverage of the "spingate" affair.

"The image put across of him bears no resemblance to the truth for people who actually know the guy and have worked with him," he said.

Blair said the resignation of his transport minister was "very sad" for Byers personally.

"People who know Steve Byers know that the millions of words that have been written about him, of an extraordinarily vicious nature, simply don't tell the truth about the person," said Blair.

The prime minister, who did not attempt to dissuade Byers from throwing in the towel, said he had been an effective and brave minister.

"He took really hard decisions on restructuring Railtrack which had to be done," he said.

"That was very difficult, but it was undoubtedly the right thing to do."

Blair's intervention came as it was claimed that yesterday's reshuffle had heightened tensions between the prime minister and his chancellor.

Sources close to Gordon Brown let it be known that the chancellor had initially wanted to draft in a loyalist to the position of chief secretary to the Treasury.

Brown is said to have had a row with the prime minister - arguing that appointments to the Treasury should be in his gift.

The chancellor is understood to have lobbied Blair to appoint the up-and-coming MP Douglas Alexander as chief secretary.

Despite losing out, Brown is said to respect tough-talking Paul Boateng, who was appointed as chief secretary yesterday.

Insiders claim that Blair ignored all the chancellor's key reshuffle recommendations - despite promoting two leading Brownites within his cabinet.

Brown was also said to be angered by the prime minister's decision to shift Yvette Cooper, the wife of his economics guru Ed Balls, to the low profile post as junior minister at the Lord Chancellor's Department.