LONDON, NOV. 24 -- Britain said today that Libya sent four shiploads of arms to Ireland for the Irish Republican Army in 1985 and 1986, but the Irish government insisted it had no evidence of Libyan involvement.

A hunt by about 7,000 troops and police for the arms ended its second day on both sides of the Irish border with no finds reported.

"Reports that these shipments of arms have come from Libya are well founded in our view," the Foreign Office said in London.

But Irish Justice Minister Gerry Collins told Ireland's parliament after the British announcement: "I have no evidence of Libyan involvement."

Police in Northern Ireland and the Irish Republic said they were holding about 45 people for questioning. Among those held were five Northern Ireland town councilors representing Sinn Fein, the legal political arm of the outlawed IRA.

Irish police said the arms hunt netted two of the 38 IRA inmates who broke out of Maze prison near Belfast in 1983. Dermot Finnucane and Paul Brennan were being held in Longford County under antiterrorism laws, police said.

Unlike Britain, which cut ties with Libya in 1984 and consistently lists it as a backer of terrorism, Ireland maintains diplomatic relations with Tripoli and has only hinted at a Libyan-IRA connection, without making outright accusations.

The mainly Roman Catholic IRA is trying to drive the British from Northern Ireland. It wants to unite the predominantly Protestant province with the 95 percent Roman Catholic Irish Republic under socialist rule.

The Guardian, a London newspaper, said security forces in Northern Ireland now assume the IRA arsenal includes Soviet-made SA7 surface-to-air missiles. Therefore, it said, antimissile devices have been fitted on Prime Minister Margaret Thatcher's aircraft, as well as all British military aircraft used in Northern Ireland.

Officials in London said information reaching here said two shiploads reached the IRA in 1985 and another two last year.