In a fresh spate of violence in Northern Ireland, a massive car bomb has partially exploded at a police headquarters in Belfast.

The car, containing a 180-kilogram bomb, failed to explode properly after crashing through barriers outside the headquarters late Saturday, a police spokeswoman said.

No one was injured in the attack nor was the headquarters damaged. The scene remains cordoned off.

"Had this device functioned, there would certainly have been widespread damage and destruction. It is also very probable that this 'no warning' device would have led to very serious injury or loss of life," the spokeswoman stressed.

In another incident in the region, police exchanged heavy fire with gunmen in the western border village of Garrison, but no one was hurt.

Three people have been arrested in connection with the ambush.

Police believes the attacks have been carried out by dissident republicans.

Northern Ireland has been largely peaceful since the 1998 Good Friday agreement brought an end to most of the violence which plagued the country for three decades, claiming at least 3,500 lives.

However during recent weeks, the Northern Ireland peace process has hit a stumbling block, following disputes between the main Protestant and Catholic parties.

In March, the paramilitary dissidents killed two British soldiers and a police officer in two separate attacks, highlighting renewed violence in the volatile region.

FF/TG/DT