LONDON -- Alastair Campbell has resigned as the government's director of communications and strategy, BBC reported.

Campbell's decision was announced by Downing Street shortly after 1430 BST on Friday.

No successor has been announced, while a date for Mr. Campbell's departure has not been set. He said: "It has been an enormous privilege to work so closely in opposition and in government for someone I believe history will judge as a great transforming prime minister." He was, is, and will remain a good friend

Campbell said his family had paid a price for his role and said his partner, Cherie Blair's aide Fiona Millar, would be leaving No 10 at the same time "in a few weeks".

Campbell he planned to write, broadcast and make speeches, but did not want to take on "another big job". Tony Blair paid tribute to his media chief, saying he was "an immensely able, fearless, loyal servant of the cause he believes in who was dedicated not only to that cause but to his country ... he was, is, and will remain a good friend."

The dramatic announcement comes amid the Hutton inquiry into the death of weapons expert Dr. David Kelly.

Campbell, a former newspaper journalist, gave evidence to the inquiry last week over the BBC report that Downing Street had "sexed up" the Iraq arms dossier.

He said: "My family, friends and close colleagues know that I have been thinking for some time about leaving my position as director of communications and strategy. "I had intended to leave last summer but as the Iraq issue developed, the prime minister asked me to stay on to oversee government communications on Iraq, and I was happy to do so."

He said he and the prime minister had agreed on 7 April that he would step down from his role this year.

"I have now given the prime minister formal notice of my decision to leave," he added.

Campbell said the decision was announced on Friday because he felt it would be wrong to do so while the Hutton inquiry was sitting.

The inquiry adjourned on Thursday and will resume on Monday.

Campbell went on: "I shall of course continue to be available to assist his inquiry in any way he wishes. "I will also be available in the next few weeks to assist the handover to my successor, who will be announced shortly."

Campbell started working with Blair after he became Labour leader in 1994.

He became the prime minister's official spokesman after Labour's election victory in 1997.

He moved to his role as communications director in 2001.