A national newspaper said a "source" carried the black 9mm weapon and blank ammunition in a bag into the heart of the prison.

A report in the paper said the bag was not searched and the carrier walked past an X-ray machine.

The gun was hidden overnight in a false ceiling in a foyer area between two sealed-off wings, the paper claimed.

Basic security lacking

The newspaper's informant was "not a serving prison officer", it said.

The pistol was smuggled in through a main entrance, past an X-ray machine, without even the most basic security checks and with no questions asked, it added.

There was no prison officer present to search the source or use the new X-ray machine, which stood idle, the paper said.

The gun was a realistic-looking Italian-made replica, the report claimed.