LONDON (AP) _ A jury convicted five Irish nationalists Wednesday of plotting to blow up 16 British hotels with bombs timed to explode one by one at the height of last summer's tourist season.

The object of the planned IRA bombing blitz was ''to create havoc and bloodshed throughout the country,'' a government prosecutor said, but it was foiled by anti-terrorist police.

The five convicts include a man found guilty earlier of a Brighton hotel blast that killed five people in an attempt to wipe out the Conservative government of Prime Minister Margaret Thatcher during a party convention.

Patrick Magee, 35; Gerard McDonnell, 34; Martina Anderson, 23; Ella O'Dwyer, 26, and Peter Sherry, 30, were convicted after a 25-day trial at London's Old Bailey criminal court of conspiring to cause explosions in the United Kingdom. All five are from Northern Ireland.

Magee, of Belfast, was also found guilty Tuesday of blowing up the Grand Hotel in Brighton in October, 1984 while Mrs. Thatcher and her Cabinet were staying there.

Despite Wednesday's convictions, Press Association, Britain's domestic news service, said the mastermind of the 1985 bomb plot remains at large.

Press Association, quoting unidentified security sources, said the man lives in Dublin, Ireland, and is known to police.

British news reports earlier in the week said security had been stepped up for politicians, members of the royal family and at military bases in Britain. Queen Elizabeth II is to appear in public Saturday at the annual Trooping the Color parade, the year's biggest display of military pageantry.

Judge Leslie Boreham said sentencing would be delayed for about two weeks pending outcome of a related case, details of which were not disclosed. It was not known how severe the sentences might be because the judge has considerable discretion.

The jury of six men and six women returned unanimous verdicts of guilty against all the defendants except Sherry, who was convicted by a majority verdict of 10-2.

Sherry, a member of the IRA's legal political wing, Sinn Fein, was identified by Press Association as ''one of the IRA's top assassins.''

Leaving the dock, he shouted: ''The British are responsible 3/8'' and then scuffled with four prison officers.

The IRA has been fighting to end Britain's rule over Northern Ireland and unite it with the Irish Republic, which is predominantly Roman Catholic. Protestants outnumber Catholics in the British province about 3-2.

During the trial, Prosecutor Roy Amlot said the five defendants plotted to blow up 16 hotels between July 19 and Aug. 5, 1985. Four of the hotels are in London and the rest are in coastal resorts.

The scheme was foiled by police who raided an apartment in Glasgow, Scotland, and discovered plans giving precise details about where the bombs were to be placed and when they were to explode.

Amlot said the conspirators planned to use sophisticated time bombs equipped with 24-day and 48-day delaying devices, so that the explosions would occur on consecutive days except Sundays over the three-week period.

Had it been successful, the bombing blitz would have resulted in ''carnage too great to contemplate,'' the prosecutor said.