One said: "If you had to choose an evening with Gordon or pulling your own teeth out with pliers which dentist would do the corrective work?"

But he went off topic to confirm that he has kept up his membership of the Labour Party and to answer an inquiry as to whether Malcolm Tucker, the foul-mouthed spin doctor in television comedy The Thick of It, is a good characterisation of Mr Campbell.

"I've never seen the programme, but people tell me Malcolm Tucker's a bit better looking. Is he?" Mr Blair responded, copying in Mr Campbell's @campbellclaret Twitter address in his reply.

He also acknowledged that his work as a Middle East peace envoy was "very tough" but that he "always knew it was going to be".

His aide, Ruth Turner, told followers that the former prime minister was personally answering the questions having been given "Twitter lessons".

Asked whether the Arab Spring would give rise to religious freedom in the Middle East, Mr Blair said: "It can do and must do because democracy only works with an open mind."

On Christopher Hitchens, the atheist writer who died of cancer in December, he said: "Chris was great, deeply spiritual if not religious. People of faith should never be afraid of secular dialogue."

Among the dozens of questions that Mr Blair chose not to answer were "how wide is the mouth of a wide-mouthed-frog?" and "if you had to choose an evening with Gordon or pulling your own teeth out with pliers which dentist would do the corrective work?".