New Adams threat dims peace hopes: Public warned not to approach these four people wanted for questioning after IRA fire-bombings

THE MURDER of an RUC officer in Belfast and a republican warning of further IRA 'spectaculars' like Wednesday's mortar attack on Heathrow airport deepened the gloom last night over Northern Ireland's peace prospects.

The statement by Gerry Adams, the Sinn Fein president, that 'the conflict is ongoing; every so often there will be something spectacular to remind the outside world' provoked Sir Patrick Mayhew, the Secretary of State for Northern Ireland, to respond: 'The gloating character of that observation seems to me to be quite despicable and a remark of profound cynicism.'

Meanwhile Commander David Tucker, head of the Scotland Yard's anti-terrorist squad, appealed for information on four people wanted for questioning about the placing of IRA incendiary devices in the West End of London last month. The two men and two women were filmed by video cameras in shops in Oxford Street. 'We are anxious to trace, interview and possibly eliminate these people from our inquiries,' he said, adding that they should not be approached by the public, who should contact the anti- terrorist hotline.

Mr Adams's comments were taken as indicating that Sinn Fein and the IRA, while professing commitment to a peace process, are still wedded to the idea of using violence to gain political ground. Much of the optimism about a possible early end to the IRA campaign after the Downing Street Declaration has now evaporated.

As if to underline the republican approach, an off-duty RUC detective was gunned down last night in a bar, presumably by the IRA. Detective Constable Jackie Hagan, 33, was killed in front of his wife as they stood in a bar at a dog-racing track in north Belfast. He was the seventh person to die violently in Northern Ireland this year.

Mr Adams's warning, given on Irish radio, that more 'spectaculars' could be expected if John Major did not break what Mr Adams called the stalemate over republican demands for direct negotiations with the Government came as British and Irish ministers, meeting in London, pledged to continue their search for progress in spite of the Heathrow attack.

Underlining the shock the attack had delivered to Anglo-Irish diplomacy, Dick Spring, the Irish foreign affairs minister, condemned the attack as 'an act of absolute depravity'. In spite of negative signs coming from the republican camp, Dublin ministers have repeatedly said they hope for an positive eventual response from the IRA.

Speaking in London yesterday, Mr Spring said of Mr Adams's attempt to justify the Heathrow attack: 'It is absolutely deplorable. If Mr Adams is talking about a spectacular just like Heathrow last night, that is not the way to progress. The vast majority of the people north and south . . . do not want further violence. Violence will not solve our problems.'

The Prime Minister told MPs in the Commons that the Heathrow attack would make 'no difference to the search for peace'.

But Mr Spring conceded for the first time that it may signal an end to the initiative. 'Perhaps they (the IRA) are giving the message to both governments that they are not going to participate,' Mr Spring said.

The ease of the Heathrow attack, in which four mortars were fired over the Heathrow police station and on to an apron of the north runway, shocked pilots and airport staff.

There was speculation at Westminster that the police station was the intended target.

Paul Condon, Commissioner of the Metropolitan Police, defended the decision to keep the airport open following the attack even though it meant that 23 aircraft took off from a runway with unexploded mortar bombs alongside.

He said 25 years' experience of terrorism in Northern Ireland had led him to believe that police could 'minimise' the risk but not neutralise it.

'I defend the decisions taken last night. If life is to go on there has to be some maturity about this debate. If the suggestion is we close down Heathrow totally every time we get a coded warning, then you will be playing into the hands of the terrorists, giving them the opportunity to close down our transport system whenever they like.'

None of the mortar projectiles exploded and they did not hit sections of the runway used by aircraft, but the British Airline Pilots Association called for a full-scale inquiry into why flights had continued for 40 minutes before the northern runway was closed.

A statement from the IRA in Dublin admitted that the mortars had been placed by an 'IRA engineering unit' and criticised the airport's authorities for not shutting Heathrow down. Claims that warnings telephoned to six news organisations contained references to a mortar attack were denied by police and Heathrow management.

Commander Tucker said it was it as not known why none of the devices exploded. 'There were very clear traces of explosive material being spilled on to the runway.'

The mortars were contained in a stolen car parked in the Excelsior Hotel car park. After their detonation, it was at least 10 minutes before the resulting fire had been put out and the mortar base discovered.

The northern runway remained closed until 9.30 yesterday morning as services from the airport tried to get back to normal.

An off-duty RUC detective was shot dead in what is believed to have been a republican attack in north Belfast last night.

The detective was shot dead around 9 o'clock while in a bar at Dunmore stadium, a greyhound track in the north of the city. He died almost immediately at the scene.

The stadium is used by a wide cross-section of society, and is known as a venue where, unusually for Northern Ireland, republicans and loyalists generally mix without antagonism.

The policeman shot is said to have been well-known in the dog-racing fraternity, having trained and raced his own dogs. His death means seven people have died violently in Northern Ireland this year.

(Photograph omitted)