NEW YORK -- The Washington Post and The Guardian won the Pulitzer Prize in public service Monday for revealing the U.S. government's sweeping surveillance programs in a blockbuster series of stories based on secret documents supplied by NSA leaker Edward Snowden.

The Pulitzer for breaking news was awarded to The Boston Globe for its "exhaustive and empathetic" coverage of the Boston Marathon bombing and the manhunt that followed.

Two of the nation's biggest and most distinguished newspapers, The Post and The New York Times, won two Pulitzers each, while the other awards were scattered among a variety of publications large and small.

The stories about the National Security Agency's spy programs revealed that the government has systematically collected information about millions of Americans' phone calls and emails in its effort to head off terrorist attacks. The resulting furor led President Barack Obama to impose limits on the surveillance.

The reporting "helped stimulate the very important discussion about the balance between privacy and security, and that discussion is still going on," Sig Gissler, administrator of the Pulitzer Prizes.

The NSA stories were written by Barton Gellman at The Washington Post and Glenn Greenwald, Laura Poitras and Ewen MacAskill, whose work was published by The Guardian US, the British newspaper's American operation, based in New York.

"I think this is amazing news," Poitras said. "It's a testament to Snowden's courage, a vindication of his courage and his desire to let the public know what the government is doing."

Snowden, a former contract employee at the NSA, has been charged with espionage and other offences in the U.S. and could get 30 years in prison if convicted. He has received asylum in Russia.

In a statement issued by the Freedom of the Press Foundation, Snowden saluted "the brave reporters and their colleagues who kept working in the face of extraordinary intimidation, including the forced destruction of journalistic materials, the inappropriate use of terrorism laws, and so many other means of pressure to get them to stop."

Snowden's supporters have likened his disclosures to the release of the Pentagon Papers, the secret Vietnam War history whose publication by The New York Times in 1971 won the newspaper a Pulitzer. His critics have branded him a criminal.

"To be rewarding illegal conduct, to be enabling a traitor like Snowden, to me is not something that should be rewarded with a Pulitzer Prize," said Rep. Peter King, R-New York. "Snowden has violated his oath. He has put American lives at risk."

At The Boston Globe, the newsroom was closed off to outsiders, and staff members marked the announcement of the breaking-news award -- coming just a day before the anniversary of the bombing -- with a moment of silence for the victims.

"There's nobody in this room who wanted to cover this story. Each and every one of us hopes that nothing like it ever happens again on our watch," Globe Editor Brian McGrory told the newsroom.

The bombing last April 15 that killed three people and wounded more than 260 also led to a Pulitzer in the feature photography category for Josh Haner of The New York Times, for his photo essay on a blast victim who lost his legs.

The Times also won in the breaking-news photography category, for Tyler Hicks' coverage of the Westgate mall terrorist attack in Kenya.

The Washington Post won a second Pulitzer in the explanatory reporting category, for Eli Saslow's look at food stamps in America.

The Pulitzers are given out each year by Columbia University on the recommendation of a board of distinguished journalists and others. The two winners of the public service award will receive gold medals. The other awards carry a $10,000 prize.

The Center for Public Integrity's Chris Hamby won for investigative reporting for detailing how lawyers and doctors rigged a system to deny benefits to coal miners suffering from black lung disease.

The prize for national reporting went to David Philipps of The Gazette of Colorado Springs, Colorado, for an investigation that found that the Army has discharged escalating numbers of traumatized combat veterans who commit crimes at home.

The Pulitzer for international reporting was awarded to Jason Szep and Andrew R.C. Marshall of Reuters for their coverage of the violent persecution of a Muslim minority in Myanmar.

The Oregonian won for editorial writing for its focus on reforms in Oregon's public employee pension fund. The prize was the third in the newspaper's history for editorial writing.

The Tampa Bay Times' Will Hobson and Michael LaForgia in Florida won in local reporting for writing about squalid housing for the homeless.

"These reporters faced long odds. They had to visit dicey neighbourhoods late at night. They had to encourage county officials to be courageous and come forth with records," said Neil Brown, Tampa Bay Times editor and vice-president. "And in the end, what they were ultimately doing was standing up for people who had no champion and no advocate."

The Philadelphia Inquirer's architecture critic Inga Saffron won for criticism. At The Charlotte Observer, Kevin Siers received the award for editorial cartooning.

No award was handed out for feature writing.

The Post's Gelman said the NSA stories were the product of the "most exhilarating and frightening year of reporting."

"I'm especially proud of the category," he said. "Public service feels like a validation of our belief in the face of some pretty strong criticism that the people have a right to take part in drawing the boundaries of secret intelligence in a democracy."