VATICAN CITY (Reuters) - Paolo Gabriele, Pope Benedict's former butler who was convicted this month for stealing papal documents and leaking them to the media, will be moved from house arrest to a Vatican jail cell, the Vatican said on Thursday.

A statement said Gabriele would moved later on Thursday to the Vatican's police station to carry out the rest of his 18-month sentence.

The Vatican said the decision to end house arrest for Gabriele, who has been living with his family in their apartment in the Vatican, was taken after both the defense and the prosecution decided not to appeal the sentence.

It said Gabriele would still be able to appeal to the pope for a pardon, which would free him from jail.

But first he had to recognize the gravity of his crime and "make a sincere request for forgiveness from the Supreme Pontiff and those who were unjustly offended," the statement said.

Gabriele, who was responsible for the most serious security breach in recent Vatican history, was sentenced to 18 months on October 6.

The prosecution had asked for a three-year term but the court gave him a lighter sentence because he had no previous criminal record.

Gabriele, 46, who served the pope his meals and helped him dressed, leaked private documents to the media.

Some of them alleged corruption in the Vatican's business dealings with Italian companies and internal conflict over the running of the Vatican bank.

The Vatican has no jail as such but has cells in the police station inside the tiny city-state.

(Reporting By Philip Pullella; editing by James Mackenzie)