A dissident republican group opposed to the Northern Ireland peace process has said it shot dead two British soldiers at an army base, the first such killing in 12 years. A man who said he was from the Real IRA claimed responsibility for Saturday night's attack at the Massereene barracks north-west of Belfast in a phone call to a newspaper using a recognised code word. The soldiers, who were set to deploy to Afghanistan on Sunday, were killed when two masked gunmen pulled up outside their barracks as a pizza delivery car arrived and fired two long bursts of automatic gunfire before fleeing. The attack has raised fears that sectarian violence could return to Northern Ireland, which has seen relative peace since 30 years of sectarian unrest which cost some 3,000 lives was largely ended with a 1998 peace accord. Figures from all parties vowed the shootings, which also wounded four, would not shake the political system put in place as part of the peace process. Deputy First Minister Martin McGuinness of Sinn Fein said the days of conflict "can never come back again". "I was a member of the IRA but that war is over now," he said. "The people responsible for last night's incident are clearly signalling that they want to resume or restart that war. Well, I deny their right to do that." First Minister Peter Robinson, of the Democratic Unionists, added that the killers had "no prospect of success in their campaign". And British prime minister Gordon Brown vowed: "No murderer will be able to derail (the) peace process." However, officials will be deeply concerned by the prospect that the Real IRA - an IRA splinter group formed in 1997 to oppose Sinn Fein's role in the peace process - is behind the attack. The group was responsible for Northern Ireland's single biggest attack, the 1998 Omagh bombing which killed 29 people. Suzanne Breen, a reporter with the Irish Sunday Tribune newspaper, said she received a telephone call on Sunday evening from a man using an "authorised code word" who said he made "no apology" for attacking the soldiers. "A man who said he was a representative of the South Antrim Brigade of the Real IRA claimed responsibility for the attack," Mr Breen told BBC television. Police are hunting three men involved in the attack - two gunmen and a getaway driver. There are reportedly up to 300 dissident republicans active in Northern Ireland. A senior security source said the shooting was a professional one which marked a "step change" in the extremist threat. * AFP