David Cameron appeared to have blundered again on Twitter, marking a highly offensive tweet as a "favourite" on his official account on the social networking site.
The tweet, from a user mocking former Tory chairman Lord Tebbit, was posted in response to the prime minister's message of condolence for victims of the Nairobi terror attack.
The prime minister warned about the danger of Twitter before he signed up to the website and it is the second time his account has been involved in an embarrassing mistake.
The error occurred after the account, run by the prime minister and Tory aides, posted a message saying he had given his condolences to Kenya's president Uhuru Kenyatta after the attack and added that Foreign Secretary William Hague would make a statement.
The reply, which was mistakenly marked as a favourite, said: "@David_Cameron please call off @WilliamHague, hasn't Kenya suffered enough today?"
The user's profile coupled an offensive username with an image of Lord Tebbit in the aftermath of the Brighton bombing.
The Mail Online website said the error was made overnight by one of the aides running the Tory leader's Twitter account.
A spokesman said: "This is a deeply offensive account that the prime minister would never want to be associated with.
"Clearly the Tweet was favourited by mistake and was removed as soon as it was realised."
In July Cameron posted a message in support of Work and Pensions Secretary Iain Duncan Smith's welfare reforms but blundered by including the name of a spoof account for the Cabinet minister.
Suspicions about the @IDS_MP account should have been raised by examining messages posted by "Iain Duncan Smith" including: "I've always supported a Mansion Tax. Your Tax buys my Mansion. Chin chin!"
Cameron was a latecomer to Twitter, having previously said he was worried that ''too many tweets might make a twat''.