Tory MP Boris Johnson has expressed his regret at being sacked as shadow arts minister amid allegations about his private life.
Mr Howard (l) with Mr Johnson (r) at The Spectator Awards this week
A spokesman for party leader Michael Howard said he was removed for lying about claims of an affair.
Mr Johnson, a married father-of-four who edits the Spectator, has also been dismissed as party vice-chairman.
He is quoted as expressing his sorrow at the decision, which he said was made in response to tabloid stories.
Mr Johnson last week dismissed claims in a Sunday newspaper that he had an affair with Spectator columnist Petronella Wyatt.
He told The Mail on Sunday: "I am very sorry this decision has been taken in response to tabloid stories about my private life."
And the Sunday Telegraph quoted him as saying: "It is a wretched and lamentable day when people's private lives become used in political machinations."
He later told the Press Association: "God. It's been a bad evening."
Mr Howard sacked Mr Johnson by telephone on Saturday afternoon amid fresh revelations in at least two Sunday newspapers.
The party leader's spokesman said the decision was made because he lied about the claims, not because of the allegations themselves.
The spokesman said: "It was nothing to do with personal morality but rather with his personal integrity and honesty."
Mr Johnson had dismissed the original allegations as "an inverted pyramid of piffle".
BBC political correspondent Norman Smith said Mr Howard questioned Mr Johnson about the claims and was not satisfied by his answers.
He said: "He feels the replies he was given by Boris Johnson were not entirely candid and honest and therefore there were questions about his integrity.
"He felt it was not appropriate for someone with those questions surrounding him to remain on the Conservative front bench."
Michael Ancram QC, the Tory party's deputy leader, told the BBC's Breakfast With Frost programme: "It wasn't about his private life, it was about something more central than that.
"Michael Howard for a long time has been talking about the need to restore people's trust in the honesty and integrity of politics.
"Where Boris was less than frank, that was what could not be sustained. In the end Michael, when he realised Boris had not been frank with him, had to let him go."
Speaking earlier this week at a Spectator awards ceremony, Mr Howard paid tribute to Mr Johnson.
He described the magazine as "political Viagra" and praised Mr Johnson for carrying out his duties with "aplomb".
He said: "I must take this opportunity of congratulating Boris on the tremendous enthusiasm with which you have approached your various front bench duties."
Ian Kirby, political editor of The News of the World, one of the papers reporting the new claims, told BBC News 24 he was surprised the party had moved so quickly to remove Mr Johnson.
He said the sacking did not spell the end of Mr Johnson's political career, but added: "It will be a while before you see him back in the upper echelons of the Conservative party."
The Spectator's political editor Peter Oborne told BBC News: "Boris Johnson is a superb figure, very much part of the Conservative Party's history, really inspirational, one of the few Tory MPs that everybody can relate to.
"I am not clear that this was a suitable reason for somebody to leave the front bench. The Tory party must have gone mad tonight."
Mr Johnson was embroiled in controversy last month when a Spectator editorial accused Liverpudlians of wallowing in grief over the murder in Iraq of engineer Ken Bigley.
The MP, whose wife Marina is the daughter of veteran BBC journalist Charles Wheeler, later visited the city to apologise.