BELFAST (Reuters) - A prison officer was killed in Northern Ireland on Thursday when he drove into a hail of bullets and crashed off a motorway at high speed, in an attack blamed by politicians on militant nationalists.

It was the first murder of a prison officer since 1993 and the fifth fatal attack on a member of the security establishment since the 1998 Good Friday peace deal, which largely ended three decades of sectarian conflict in Northern Ireland.

The officer worked at the top security Maghaberry Prison where militant nationalists have been protesting against their living conditions. Prison officers had stepped up their personal security in recent months.

Forensic experts were examining a car found burned out near the motorway which police said may have used in the attack.

"Actions like this have no place in society and those who carried out this murder have nothing positive to contribute," Northern Ireland's First and Deputy First Ministers, Unionist Peter Robinson and Sinn Fein's Martin McGuinness, said.

"We refuse to let the people behind the attack divert us from building a better and peaceful future for everyone," they added in a joint statement. Irish Justice Minister Alan Shatter said he condemned utterly "the brutal and barbaric murder."

More than 3,600 people were killed in Northern Ireland's "Troubles", when Catholic nationalists seeking union with Ireland fought British security forces and mainly Protestant Loyalists determined to remain part of the United Kingdom.

Militant nationalists remain active and have stepped up attacks in recent years. Two soldiers and a policeman were shot dead in the space of three days in March 2009, and another policeman was killed by a car bomb in April 2010.

(Reporting by Ian Graham, Writing by Padraic Halpin, Editing by Mark Trevelyan)