Police have launched a fresh bid to catch the gunmen who killed two soldiers in Northern Ireland, as a terminally ill man convicted of trying to torch their getaway car was told he must serve a minimum of 25 years in jail.

Brian Shivers, 46, from Magherafelt, Co Londonderry, who was part of the Real IRA gang that murdered Sappers Patrick Azimkar, 21, and Mark Quinsey, 23, outside the Massereene military barracks, is suffering from cystic fibrosis and has an estimated four to five years to live.

He was sentenced to life imprisonment last month and on Friday at Belfast Crown Court Mr Justice Anthony Hart told him he would have to spend at least 25 years in prison before he could be considered for release.

Sapper Quinsey, from Birmingham, and Sapper Azimkar, from London, both serving with 38 Engineer Regiment, were about to leave for a tour in Afghanistan in March 2009 when they were gunned down by dissident republicans opposed to the Good Friday peace deal.

The judge said: "I am satisfied that appropriate arrangements are being put in place to provide the necessary medical care which Shivers will require in the future. Those involved in this very grave crime must receive appropriate punishment."

He said Shivers was deemed to be a secondary party to the killings, responsible for making a failed effort to burn out the getaway car.

But he added: "Whilst he played a lesser role than the gunmen and the driver of the attack car, by being at Ranaghan Road and setting fire to the car, he played a prominent and essential role in this carefully planned and ruthlessly executed crime."

The judge quoted from victim impact statements presented to the court by the families of the murdered soldiers.

Sapper Quinsey's mother, Pamela, said: "A mother thinks she will hold her child's hand for the rest of her life. Now my hand is empty and lost."

Sapper Azimkar's mother, Geraldine, said: "We have all changed, all aged, our hearts and souls are no longer light but weighed down with sorrow and loss."