Updated

Prime Minister Tony Blair's powerful communications chief Alastair Campbell (search), a central figure in the controversy over whether Britain exaggerated the Iraqi weapon threat to justify war, announced Friday that he will resign.

In a statement issued by Blair's office, Campbell said he intended to step down in "a few weeks" for family reasons. He said a replacement would be announced "shortly."

A former tabloid journalist who has worked for Blair since 1994, Campbell is often referred to as "the real deputy prime minister" and depicted as a shadowy and Machiavellian power behind the government.

In a statement, Blair said "the picture of Alastair Campbell painted by parts of the media has always been a caricature."

He praised Campbell as "an immensely able, fearless, loyal servant of the cause he believes in who was dedicated not only to that cause but to his country."

Campbell was at the center of media allegations that Blair's office exaggerated the threat posed by Iraqi weapons in an intelligence dossier used to win support for military action against Iraq.

He has denied the allegations, and intelligence chiefs have backed up his version of events.

But his decision to step down is likely to be seen as an admission that somebody in government must accept blame for what has become the biggest crisis in Blair's six years in power. The dispute over Iraq and the death of a key government scientist caught up in the crisis has damaged public trust in Blair and the government.

In an interview after his announcement, Campbell said the decision had nothing to do with the controversy.

"I have been thinking and talking about leaving for some time," he said. "I wanted to go a year ago and the prime minister asked me to stay on because the Iraq issue was developing in a particularly alarming way and we agreed back in April that I would definitely go this summer."

Campbell appeared last week before a judicial inquiry into the death of government weapons adviser David Kelly (search), who apparently committed suicide after being identified as the source of a British Broadcasting Corp. report on the government's Iraq policy.

The report alleged that Blair's office inserted a claim that Saddam Hussein could deploy weapons of mass destruction within 45 minutes into a September dossier against the wishes of intelligence officials.

In a later newspaper column, the BBC journalist Andrew Gilligan (search) named Campbell as the official behind the insertion. Campbell called the BBC report a lie.

A Cambridge University graduate who once contributed stories to an erotic magazine, Campbell was political editor of the Daily Mirror before being named spokesman to Blair — then leader of the opposition — in 1994.

After the Labor Party came to power in 1997, Campbell forged a formidable Downing Street press machine to sell the government's agenda to the public.

The technique sometimes backfired; many journalists disliked what they perceived as Campbell's heavy-handedness and accused the government of being obsessed with spin rather than substance.

Campbell, for his part, seemed to find journalists tiresome.

"The media are obsessed with spin-doctors, and with portraying them as a bad thing, yet seem addicted to our medicine," he once said.

In 2000, he stepped back from his role as official spokesman to become Blair's director of communications.

Campbell said his girlfriend, Fiona Millar, a media adviser to Blair's wife, Cherie, would resign at the same time to return to a career in journalism. The couple have three children.