Three Vatican figures, including two senior members of the clergy, have been named as suspected moles in a scandal that has seen the Holy See rocked by a series of damaging leaks.

The new intrigue comes just days after Pope Benedict's butler Paolo Gabriele, 46, was released from jail and placed under house arrest for his suspected part in the affair.

The new suspects are reported to be Cardinal Paolo Sardi, a former Papal speechwriter; Bishop Josef Clemens, the Pope's former personal assistant; and the Pope's German housekeeper Ingrid Stampa. The latter is said to be among the few people at Holy See able to decipher the pontiff's handwriting, according to the newspaper La Repubblica.

Mr Gabriele has been blamed by Vatican investigators for passing on sensitive documents that have led to the widespread publication of reports claiming nepotism, death threats, gay smear campaigns and tax irregularities at the Holy See. One of the leaked documents suggested Pope Benedict's new ambassador in Washington was exiled in the US because he had blown the whistle on financial corruption.

The Vatican admits that nearly 30 people have been questioned in the probe so far. But it insists that Mr Gabriele remains the only person officially under suspicion.

No one at the Vatican was available yesterday to comment on the fresh claims. But speaking on Vatican Radio, chief spokesman Father Federico Lombardi denied there were further suspects. He said the claims in La Repubblica were merely copied from earlier speculation in the German press. Most Vatican experts doubt, however, that the Pope's butler could or would have acted alone in identifying sensitive documents (some in German), stealing them and delivering them to Italian journalists.

"No one here believes the official Vatican line," said Robert Mickens, the Rome Correspondent of Catholic newspaper, The Tablet. "There's no one, and none of my colleagues working at the Vatican, who thinks that Paolo Gabriele could have acted alone. He was clearly working with, or more likely for, one or more persons higher in the pecking order, and that means bishops and senior church figures."

Many Vatican observers suggest the damaging leaks are part of a campaign against the Pontiff and his equally unpopular number two, the Vatican Secretary of State, Cardinal Tarcisio Bertone.

At the weekend Mr Gabriele was released from the Vatican jail having spent 60 days in detention, and placed under house arrest. His father insisted on his son's innocence. But the papal butler's lawyer claimed at a Vatican press conference that his client acted on his own initiative when he took the documents and stashed them in his Vatican apartment.