Asked if he would quit, Roger Houchin replied bluntly: "Absolutely not."

He said the jail had 75,000 movements in and out every year and it had maintained an "enviable" security record.

Roger Houchin is asked if he is considering resigning

"It just happens that two quite unrelated incidents occurred in two weeks and I don't make excuses for that - they shouldn't have happened.

"We will take whatever steps we can to improve the situation."

Urgent inquiry

Alexander Logan, 49, was freed on 19 October, a spokesman for the Scottish Prison Service reported.

Strathclyde Police said he was arrested in the Lanark area on Saturday.

Just days after Mr Logan's release a man facing a murder charge was freed in error from the same jail.

Roger Houchin: "Two unusual occurrences"

The SPS spokesman said Mr Logan's absence was not noted until 27 October.

He was on remand on charges of assault and breach of the peace.

The spokesman added: "That's two mistaken releases in two weeks and we do not find that at all acceptable. There's a full and urgent inquiry under way."

Awaiting trial

On Wednesday, Stuart Quinn, 25, who is accused of stabbing a man to death, was "liberated in error" from Barlinnie.

Mr Quinn, who is awaiting trial for murder, was able to leave the prison just days before the trial and return to his home in Craigneuk, near Wishaw in Lanarkshire.

He was remanded in custody at Hamilton Sheriff Court last June charged in connection with the death of David John Kane, 19, on 20 April 1998.

Mr Quinn subsequently gave himself up to police in Glasgow.

Minister angry

Scottish Home Affairs Minister Henry McLeish said: "I am very angry about this matter.

"For two prisoners to be released in error within a matter of days is totally unacceptable. This simply should not happen.

"The public deserves to be protected and in view of my concerns I have asked the Scottish Prison Service's chief executive to have a full report on my desk on Monday morning."