Their now-closed weekly journal, Unity, published a story in January claiming a large and clandestine factory was built in Myanmar to produce chemical weapons. It quoted workers at the factory in northwestern Myanmar and mentioned the presence of Chinese technicians.
The sentence, a conviction under the 1920s-era State Secrets Act, is seen as a setback to long-sought press freedoms won after five decades of censorship, and the case is regarded as a reversal from independent journalism to bullying tactics by the government, led by former military officers.
A police unit known as the Special Force has visited newsroom in recent weeks with demands to see financial records, and a journalist for an online news site was jailed for trespassing and disturbing a civil servant.
"This is injustice! This is an attempt to control the press!" Unity executive editor U Tint Hasan said in court after the sentences were read.
Myanmar President Thein Sein, who re-instituted press freedom when he came to power in 2011, has reverted to a hardline approach, saying in a speech broadcast Monday, "If media freedoms are used to endanger state security rather than give benefits to the country, I want to announce that effective action will taken under existing laws."