The National Gallery of Art has acquired a major painting by the southern baroque master Jusepe de Ribera, gallery Director J. Carter Brown announced yesterday.

The 1634 painting, "The Martyrdom of Saint Bartholomew," was purchased by an agent on behalf of the gallery's 50th Anniversary Committee at Sotheby's in London last summer for 2.75 million pounds ($4.9 million). It is the first Ribera to enter the museum's collection.

"This is the end of a long quest," said Brown. "We wanted to get something worthy of our collections and needed by them. In the context of the art market today, it was unlikely we would have found something quite as major that we could still afford."

The privately funded committee, which is chaired by National Gallery trustee Robert H. Smith, was set up to raise funds to acquire works of art for the gallery's 50th anniversary next year. It had targeted the areas that Ribera, a Spanish artist working in Italy, represents. "The gallery's collections have a relative weakness in two areas: one in 17th-century baroque art, which is primarily Italian, and another in Spanish art," said Brown. "And this picture helps us in both categories at the same time."

No announcement of the gift could be made until yesterday, when the British department of trade and industry issued the export license needed to allow the painting to leave the country. "We'd been holding our breath since the middle of July and had become quite blue," said Brown. "We're grateful to the British authorities."

Scholars consider the painting to be one of Ribera's finest. It has been in private hands for almost 200 years.

"We've always wanted a major Ribera," said Diane De Grazia, the gallery's curator of southern baroque painting. "To have a major example from the major exponent of the Neapolitan 17th-century style is fantastic. I am thrilled."

The flaying of Saint Bartholomew was a popular subject in 17th-century Italian painting, and Ribera painted many versions of the subject. This one, which is 41 inches high by 44 1/2 inches wide, depicts the moment before the apostle's martyrdom, when the executioner is sharpening his blade.

"You wouldn't expect a subject so grisly to translate into a work of art, but what's going on here is the extraordinary intensity of the moment," said Brown. "You can see it on the executioner's face."

"The painting is also important because of its remarkable state of preservation," said De Grazia. "Many of Ribera's paintings have suffered, but in this case the benign neglect of sitting in a country house for hundreds of years is what has saved it."

The painting will go on view to the public on March 17, as part of the exhibition "Art for the Nation: Gifts in Honor of the 50th Anniversary of the National Gallery of Art."