The Russian government will spend more than $170 million to expand and modernize the Pushkin State Museum of Fine Arts, the museum’s director said Tuesday.

The Pushkin Museum is Moscow’s leading collection of Western European art, and owns about 650,000 items. It attracts about 1 million visitors a year, and has one of the finest collections of French Impressionist and post-Impressionist paintings, with major works by Matisse, Monet, Picasso, and Van Gogh.

The museum has the backing of the Foundation for Support of the Pushkin Museum of Fine Arts, a private organization that was headed by Dmitry Medvedev until he became president of Russia in May.

“President Medvedev has been deeply involved in getting this support, for which we are very grateful,” the museum’s director, Irina Antonova, said in an interview. The money, given over three years, “will help us expand and reconstruct the museum as part of plans to mark our centenary in 2012.”

In November, the museum approved plans by British architect Norman Foster to add 1.2 million square feet to the museum’s current 430,000 square feet. The Pushkin aims to mark its centenary in 2012 with four new buildings on adjacent land within sight of the Kremlin, and the renovation of several decrepit tsarist-era structures.

Ms. Antonova, who has served as Pushkin director since 1961, said that the presidential grant will be officially approved in the second half of June or early July. The total cost of the museum’s expansion will be “at least” $400 million, and the project will require a second phase lasting from 2012 to 2015 that will need additional financing, she said.