Two of the devices had been planted under the politicians' cars. One of them exploded, while the other was discovered and defused by the Army. Within an hour, a third device went off at a house yards from the home of another politician. No one was hurt in the attacks.
The Ulster Freeedom Fighters, a loyalist paramilitary group, later claimed responsibility for the attacks in a call to the BBC, saying that three of its active service units had planted 1lb devices. The incidents bring to nine the number of SDLP members who have been targeted this year since the UFF said it would step up its violence against what it called the 'pan-nationalist movement', linking the SDLP, the Irish government, the IRA and Sinn Fein.
Security experts said the Royal Ulster Constabulary believed a young and ruthless clique had gained control of the UFF, which is increasingly resourceful - as demonstrated by its ability to use explosives and operate in a co-ordinated fashion.
The first device exploded shortly before 1am under the Renault car of the SDLP MP, Dr Joe Hendron, which was parked outside his home in west Belfast. 'My wife heard this hissing sound and immediately afterwards there was a loud explosion,' he said. 'We knew at once it was a bomb. We ran to the window and there was smoke coming from the car.'
The MP, his wife and two children, were not hurt in the blast, which caused serious damage to the car.
Shortly afterwards, a bomb was found under the car of Dr Brian Feeney, a leading SDLP member who resigned his seat on Belfast council at the last elections. Bomb disposal experts carried out a controlled explosion. Dr Feeney, who was away on holiday, returned home when told of the attack.
About an hour later, a third bomb exploded at a vacant house several doors away from the home of another SDLP councillor, Mary Muldoon.
During the past six months there have been bomb attacks on the homes of six SDLP members in Banbridge, Ballymena and Belfast.
Later Seamus Mallon, deputy leader of the SDLP, condemned the attacks, which he said were not just against his members but the entire political process.
He said: 'The brave men and wom en who serve in constitutional politics in Northern Ireland will continue to do so. We will win out over the terrorists who have nothing in their armoury but the bomb and bullet.'