The Boston Museum of Fine Arts -- which last year borrowed more than $1 million to pay for its half-share of Gilbert Stuart's portraits of George and Martha Washington -- is now being forced to sell a dozen paintings to pay off its debt.

The museum hopes to raise between $1.3 million and $1.7 million by selling the pictures from its permanent collection -- among them two Renoirs, a Monet, and two Bierstadts.

"We sell paintings every day. It's no big deal," a museum official said.

Boston last year paid $2,125,000 for the right to show the Stuarts three years out of six. Today it owns them jointly with the Smithsonian Institution's National Portrait Gallery, where they are now on view.

That compromise resolved a bitter year-long battle between the two museums, both of which had hoped to buy the famous portraits -- asking price: $5 million -- from the Boston Atheneum. They had been on loan since 1876 to the Museum of Fine Arts. But despite a "Save Our Stuarts" fund drive, Boston, in the end, found it could not raise the cash.

"We raised about $1 million from a variety of sources," said the museum's director, Jan Fontein. "A bank lent us the rest."

In order to repay that debt, 12 well-known Boston pictures have been consigned for sale to Sotheby Parke Bernet, the Manhattan auctioneers. In addition, a 13th Boston painting -- John Singleton Copley's "Lady in Blue" (1763) -- was sold privately last week by Manhattan's Kennedy Galleries. The price was not disclosed.

Eight of the Boston pictures, all of them American, will go on the block on Thursday. The auctioneers expect that set of eight to sell for between $460,000 and $620,000.

They include an 1808 Robert Salmon seascape, "Ceres,' Privateer of Liverpool," (presale estimate: $30,000-$40,000); "At the Fishing Grounds," an 1851 seascape by the luminist Fitz Hugh Lane ($100,000-$125,000); "View of the Catskills," an 1844 landscape by Asher B. Durand ($50,000-$75,000); "Early Autumn on the Hudson," 1873, by Jasper Francis Cropsey ($20,000-$25,000); James Goodwyn Clonney's "What a Catch," 1855, ($75,000-$100,000); "The Bay of Panama," circa 1871, a luminist sunset scene by Martin Johnson Heade ($75,000-$100,000); and two Albert Bierstadts, "Snow Scene with Buffaloes," circa 1867-1868 ($50,000-$75,000), and "Moose Hunter's Camp, Nova Scotia," circa 1875-1878, which the auctioneers expect to sell for a sum between $60,000 and $80,000. Two of these paintings -- the Cropsey and the Bierstadt "Snow Scene" -- come from the museum's now-diminished M. and M. Karolic Collection of American pictures, which, when formed, was perhaps the single most important such collection in the world.

Four impressionist paintings will be auctioned May 21. They are Renoir's "L'Estaque," 1882, ($300,000-$400,000); Renoir's "Garden at Mezy," 1891, ($300,000-$350,000); Alfred Sisley's "Road to Moret," 1882, ($150,000-$200,000) and Claude Monet's "Wheatfields," 1873, ($120,000-$150,000).

All the pictures to be sold, said Fontein, have been "personally" inspected by the museum's board. "I can assure you," he added, "that if the pictures sell as well as we expect them to, that will be the final end of the George and Martha story."