LONDON -- The Irish Republican Army set off a fire bomb yesterday inside the National Gallery, one of the world's premier art museums, but none of the institution's priceless paintings was damaged, police reported.

The bomb was set off about 3:30 a.m. in the bookshop of the museum's new Sainsbury wing, presumably by a timing device, but it did little damage, according to director Neil MacGregor.

The National Gallery was able to open its doors to the public later yesterday, and visitors were able to see the acclaimed renaissance collection above the bookstore and a special showing of the queen's pictures in a gallery below the bomb site, which was just off the street entrance hall.

Yesterday's fire bombing followed three fire bomb explosions in department stores in northwest London Saturday, which caused slight damage and no injuries.

Scotland Yard detectives said that the IRA was using teams of young women to plant incendiary bombs in a Christmas-season campaign to disrupt life in the capital and to damage the economy by disrupting shopping.

In admitting responsibility for the blasts, the IRA declared in Dublin, Ireland, that "active service units" had carried out the London attacks.

Members of Parliament demanded yesterday that Home Secretary Kenneth Baker crack down on the "scourge and menace" of the IRA.

"They must be a very, very sick people to attempt an exercise like that," said Ivor Stanbrook, a Conservative member of Parliament.