INTELLIGENCE officers have warned ministers that the IRA is seeking a new generation of weapons while it is raising the prospect of a ceasefire.

Sources said the IRA's priority was to buy Stinger ground-to-air missiles which were capable of knocking down army helicopters, a vital means of moving men and equipment in hostile border areas. One source said intelligence agencies had intercepted the IRA in an attempt to buy a Stinger. 'They approached a dealer, but fortunately, we got to him first, and prevented the sale going ahead.'

The IRA is reported by the intelligence sources to be seeking arms on the international market, which is swamped with weapons from the former Soviet Union. The IRA's active search for more weapons has made ministers highly sceptical of the IRA-Sinn Fein hints of a ceasefire, which is confidently expected in Ireland.

British intelligence sources believe the IRA is keen to restock its caches of arms, partly supplied by Libya until the capture of the supply ship Eksund in 1987.

The sources said some of the arms have been seized by security forces on both sides of the border; others need replacing; and SAM-7 ground-to-air missiles, which the IRA was feared to have, are less accurate than Stingers.

The disclosure of the IRA's efforts to rearm will be seen as part of the Government's efforts to counter Sinn Fein's propaganda offensive about a possible peace initiative. But ministers insist that the IRA has not scaled down its campaign of terrorism in Ulster, and it has proved that its mainland capacity 'remains undiminished'.

Ministerial sources have said they fear an upsurge in violence in the autumn when it becomes clear that hopes of peace have gone.

Ministers want to maintain a united front with the Dublin government against pressure from Sinn Fein for a response to a limited ceasefire by withdrawing British troops from Ulster. Both governments have maintained the policy, stated in the Downing Street Declaration, that Sinn Fein will only be admitted to talks after a permanent cessation of violence.

Sussex Police said yesterday that two bicycles used in the IRA bomb attacks in Bognor Regis and Brighton, last weekend were hired from a shop in Victoria, central London by two men.