A terrorist bomb-maker who infiltrated the British military should receive a tougher sentence, a former armed forces minister has said.
Mike Penning described former Royal Marine Ciaran Maxwell as a "very dangerous terrorist" and called on the Attorney General to review his 18-year jail term.
In a letter to Jeremy Wright QC, Mr Penning said Maxwell could be released in six years, something which he said "cannot be allowed to happen".
Maxwell was jailed last week for supplying bombs to dissident republicans.
"He stashed anti-personnel mines, mortars, ammunition and 14 pipe bombs - four of which were later used - in 43 purpose-built hides at eight locations in Northern Ireland and England.
Mr Penning, a former soldier, wrote to Mr Wright, saying: "I believe that the terrorism charges together with the large number of crimes he committed justifies a longer sentence.
"He admits to stealing British army ordnance with intent for it to be used against innocent people of the United Kingdom, stockpiling and supplying to terrorists pipe bombs which he manufactured using skills gained in training as part of the elite Royal Marines and all the time being a traitor to his country and fellow service personnel.
"I agree with Commander Dean Haydon, head of the Metropolitan Police Counter Terrorism unit that Mr Maxwell is an extremely dangerous terrorist."
He added: "This is an appalling situation where this man has used his privileged position in the highly respected Royal Marines to turn against his country and his colleagues to make and supply bombs intended for use against innocent people.
"If this hadn't been stopped who knows what horrors could have been perpetrated.
"With an 18-year sentence, he may well be out in six years. This cannot be allowed to happen. He is a very dangerous terrorist."
Maxwell, 31, who is originally from Larne in Co Antrim and was with 40 Commando based at Norton Manor Camp in Taunton, Somerset, at the time of the offences, was handed an 18-year jail term with another five years on licence at the Old Bailey on July 31.
He pleaded guilty to preparation of terrorist acts between January 2011 and August last year, possessing images of bank cards for fraud and possessing cannabis with intent to supply.
PSNI Detective Chief Inspector Gillian Kearney said Maxwell used his military know-how to accumulate and construct his devices, and described the infiltration of the military by a republican terrorist as "very unusual" and "certainly the first case of its kind in recent years".
Police also fear weapons he constructed may still be in circulation, ready for deployment by dissident republicans, with some of his stash potentially able to make an explosive larger than the 1987 Enniskillen bomb.