While British Prime Minister Margaret Thatcher addressed a joint session of Congress yesterday, about 1,500 demonstrators gathered outside the Capitol to demand the withdrawal of British troops from Northern Ireland and to denounce what they called her "regime of terror and murder."

"Your presence is a message against tyranny and oppression, which Mrs. Thatcher represents," Michael Flannery, an admitted gunrunner for the Irish Republican Army and former grand marshal for New York's St. Patrick's Day Parade, told the protesters.

"There will never be peace in Ireland until Britain gets out," he said. "They've been there for 800 years, and what have they given that country but blood and degradation and torture?"

The demonstrators, many Irish-Americans carrying signs and flags and chanting slogans, came by the busload from as far as Michigan and Massachusetts. They gathered near a podium set up at the East entrance to the Capitol grounds -- between the Supreme Court and the Library of Congress on First Street -- where they were addressed by a host of IRA supporters and others demanding "freedom for Northern Ireland" and the banning of plastic bullets used by British soldiers.

U.S. Capitol Police, who closed the unit blocks of First Street and the 100 block of East Capitol for the protest, said there were no arrests.

After Thatcher's address, the protestors were joined by a small group of congressmen who denounced her government's policies in Ireland.

"Her speech was one that was committed to the U.S. and reinforced her commitment to freedom for people all over the world," said Rep. Mario Biaggi (D-N.Y.), chairman of the Ad Hoc Congressional Committee for Irish Affairs. "Why not for the people of Ireland?" he asked.

Biaggi and others took exception to Thatcher urging Americans not to give financial aid to the IRA because the money is "used to buy the deaths of Irishmen, north and south of the border."

Biaggi countered that "the money raised here goes to the wives and unfortunate children of those who have been killed in the fight for justice."

Martin Galvin, a spokesman for the Irish Northern Aid who is banned from visiting Ireland, said "The real culprits of supplying money for arms in Ireland are the British taxpayers, who are paying for the 30,000 soldiers there."

Galvin said one purpose of the demonstration was to protest the U.S. State Department's refusal to grant a visa to Gerry Adams, president of Sinn Fein, the political wing of the IRA, and a member of the British House of Commons. Ten members of Congress wrote to Adams and extended an invitation for him to address Congress, Galvin said.