DUBLIN (Reuters) - Over 30 years of conflict, the IRA has grown into a tightly disciplined paramilitary group, fighting the British, imposing its own harsh vigilante justice in nationalist areas and managing a lucrative criminal empire.

No small wonder then, that many view the Irish Republican Army's declared abandonment of armed struggle with scepticism. The republican group has downed arms several times before, only to take them up again, sometimes literally digging them up, years or generations later.

"They definitely haven't gone away. It's very clear from the statement that the IRA Army Council is still in control and telling people what to do," said James Dingley, lecturer on terrorism and political violence at the University of Ulster.

"To maintain that degree of control they are going to have to maintain some kind of arms."

The IRA announced on Thursday an end to its armed campaign against British rule in Northern Ireland but sceptical Protestant Unionists who want to retain British links, and indeed many Catholics, will take some convincing.

"Too often in the past seven years we have witnessed promising statements followed by false dawns," said Fine Gael, the main opposition party in the Republic of Ireland.

"The sincerity of the provisional movement will be judged by the actions it takes to implement this latest statement."

Since emergence as the official army of a fledgling Irish state during the 1919-1921 Anglo-Irish War, the IRA has fought several campaigns to end British rule in Ireland, accusing authorities of treating Catholics as second class citizens.

"They have never gone away and have always made it very clear to their supporters that they won't," said Dingley. "They just keep a low profile for a while."

Even after the IRA was outlawed in Ireland in the 1930s and relegated to the political wilderness for several decades, a spate of bombings in Britain in 1939 and a border campaign in the 1950s served as reminders it had not gone forever.

"The very nature of their history means a large majority of people in Northern Ireland are just not going to believe them," Dingley said.

SECURITY BLANKET

That, combined with a tendency to sprout new branches with every defeat or truce means that even in its Catholic, working class strongholds, few realistically expect guns and crime to disappear from Northern Ireland politics any time soon.

"The statement will be met with apathy. We've heard it all before," said former IRA member Tommy Gorman. "The IRA have become thugs and bullies and upset a lot of people so the main reason they will need weapons is as a security blanket."

The high profile murder of Catholic father-of-two Robert McCartney earlier this year damaged the IRA's historic role as a guardian against British brutality and Protestant persecution.

Despite a 1997 ceasefire, local brigade commanders are still seen as tough controllers, using vigilante punishment beatings and knee-cappings to maintain their grip on nationalist areas.

The group, which was blamed for a massive 26.5 million pound bank heist in Belfast last year, will also find it difficult to abandon a lucrative criminal empire that has amassed assets believed to total tens of millions of pounds.

"Throughout the conflict they needed people to be fundraising, but now that machinery has become bigger than the whole of the rest of the movement," said Gorman who now works for a cross-community group in divided west Belfast.

DIVIDE AND RULE

The IRA will also be acutely aware that, on both sides of the sectarian divide, compromise is invariably interpreted as weakness and change is often seen as an act of betrayal.

As recently as 1969, the group splintered into Official IRA, which declared a full ceasefire in 1972, and Provisional IRA, responsible for about half of 3,600 deaths during the 30 years of conflict that followed.

Further ceasefires in the 1990s also created a fertile recruiting ground for dissidents such as the Real IRA which killed 29 people in the 1998 Omagh bombing and is believed to have been behind a London car bombing as recently as 2001.

The IRA's track record and many incarnations are keenly felt in Northern Ireland, where memories are slow to fade and tensions reach fever pitch every summer as Catholics are taunted by Protestant celebrations of centuries-old military victories.

"The rhetoric of history is very high in Northern Ireland compared to almost any other country," said Paul Bew, Professor of Irish History at Queen's University, Belfast. "Whether it's true history is another matter."