Vietnam jailed a well-known political blogger and his assistant on Wednesday for abusing democratic freedom, their lawyer said, in a verdict that stirred public interest and a mix of concern and criticism from rights groups and the United States.

Blogger Nguyen Huu Vinh and assistant Nguyen Thi Minh Thuy were imprisoned for five and three years respectively for posts that a Hanoi court said were abuses of their freedom and infringements upon state interests. Both had denied any connection with the blogs.

Vietnam has been widely rebuked for its tough moves to curb online dissent as public appetite for the Internet soars and Web users turn to blogs to read about issues that state-controlled media avoids.

Lawyer Ha Huy Son said the ruling was unfair and the pair would likely appeal.

"The evidence used during the trial and evidence cited in the verdict were different," Son told Reuters. "The evidence referred to in the verdict had not been verified ... there was no time to respond."

Vinh was once a policeman and private investigator. He is the son of a late cabinet minister and former ambassador to the Soviet Union.

The one-day trial was held under tight security and some protesters were seen gathering at the court.

The verdict is likely to frustrate Western governments that have stepped up diplomatic support and engagement with Vietnam while urging it to stop the arrest, imprisonment and intimidation of its critics.

The U.S. embassy in Hanoi said the use of criminal laws to stifle free speech was "disturbing".

"We call on the government to release unconditionally these two individuals, as well as all other prisoners of conscience, and allow all Vietnamese to express their views peacefully, without fear of retribution," it said in a statement.

Vietnam has recently agreed several big trade accords, including ones led by the United States and European Union. It is Southeast Asia's biggest exporter to the United States, sending some 1,700 containers there daily carrying televisions, smartphones, brand-name clothes and farm and fisheries produce.

Shawn Crispin, Southeast Asia's representative for the New York-based Committee to Protect Journalists, said the ruling was "a travesty of justice".

"If Vietnam wants to be seen as a responsible member of the international community and reliable partner in multilateral agreements, including the pending Trans-Pacific Partnership trade pact, these types of bogus anti-state convictions must stop immediately," Crispin said.