HANOI, Vietnam (AP) — A Vietnamese court issued jail sentences ranging from four to 12 years yesterday to three bloggers who wrote about human rights abuses, corruption and foreign policy, intensifying a crackdown on citizens' use of the Internet to criticise the government.

The cases are particularly high-profile examples of the Communist government's attempts to stifle challenges to its authority on the Internet, which has emerged as a major avenue for dissent in the country of 87 million people. President Barack Obama has mentioned one of the defendants, and the mother of another died after setting herself on fire to protest her daughter's arrest.

The defendants, two men and one woman, are founding members of the "Free Journalists' Club," a group of citizen journalists who posted their work on the Internet. They were found guilty of spreading "propaganda against the state."

Nguyen Van Hai, who has written under the pen name Dieu Cay or "Tobacco Pipe," got 12 years, Ta Phong Tan received 10 years and Phan Thanh Hai got four years, according to defense lawyer Ha Huy Son.

The trial in Ho Chi Minh City lasted less than six hours. The country regularly convicts dissidents, but sentences have generally been around five years.

The United States, which is seeking closer economic ties with Vietnam but is also pressing it on human rights, quickly criticized the sentences. Obama mentioned Nguyen Van Hai's case in a May speech that called for greater freedom for media around the world.

"The government's treatment of Dieu Cay appears to be inconsistent with Vietnam's obligations under the International Covenant on Civil and Political Rights, as well as the provisions of the Universal Declaration of Human Rights relating to freedom of expression and due process," it said in a statement.

Nguyen Van Hai criticised the government for its handling of tensions with neighboring China over disputed islands in the South China Sea.

Tan, a former police officer, wrote a blog called "Justice and Truth" that criticised police abuse of power. Her mother set herself on fire in protest of the case in late July.

International rights groups have condemned the trial and called for the release of the defendants.

"These harsh sentences against bloggers are absolutely outrageous, and show the depth of the Vietnam government's intolerance of views that oppose its own," said Phil Robertson from Human Rights Watch. "Today's sentences show how deep-seated the Vietnam government crackdown on basic human rights really is."