HANOI (AFP) - A Vietnamese court Friday jailed two dissident lawyers for up to five years in the latest of a series of high-profile trials against political activists that has angered the international community.

Nguyen Van Dai, 38, and Le Thi Cong Nhan, 27, were convicted of spreading propaganda against the state by the Hanoi People's Court in a trial watched by foreign media and diplomats via closed-circuit television.

Dai was sentenced to five years in jail and Nhan to four years. The two pro-democracy activists, who were arrested on March 6, face an additional four and three years' probation respectively.

The hearing, which came ahead of a May 20 national assembly election, was the latest against members of the underground Bloc 8406 pro-democracy movement, named after the date it was launched, April 8 of last year.

Scores of police guarded the courthouse and surrounding city blocks, and at least one unidentified woman was detained, according to a foreign diplomat and an online report from an overseas-based dissident group.

The arrests and trials have sparked international protests and raised tensions between Washington and Hanoi ahead of a visit by Vietnam's President Nguyen Minh Triet to the United States scheduled for next month, with some US lawmakers calling on Washington to re-impose sanctions.

European Union diplomats, eight of whom watched the Hanoi trial, welcomed access to the hearing and that the defendants were represented by lawyers but condemned the trial itself as well as the verdict. 

"We believe no one should be sent to prison for peacefully exercising their rights, as guaranteed by the Vietnamese constitution and international human rights law, to freedom of expression and association," said one EU diplomat.

"Therefore we call on the Vietnamese government to release Nguyen Van Dai, Le Thi Cong Nhan and other prisoners of concern to the EU," said the diplomat, who was speaking outside the court on condition of anonymity.

Vietnam says it does not punish anyone for their political views and only prosecutes criminals for breaking the law -- in this case Article 88, which bans the dissemination of anti-state propaganda.

The recent series of arrests and trials, and state media reports on the cases, have signalled an assertive line from Hanoi against those who challenge the political monopoly of the Communist Party.

Court president Nguyen Huu Chinh said Dai and Nhan had "distorted democracy and human rights in Vietnam, and spoken ill of socialism."

Prosecutors also said the two lawyers had "called on the people to boycott the 12th national assembly election" and had tried to convince students and staff at Dai's Thien An law firm to join their political activism.

The defendants, in comments that were often difficult to hear via the audio feed, rejected the charges.

"I did not speak ill about the party and the state," said Dai. "I just exchanged my ideas about the situation in Vietnam... I reject all accusations by the prosecutor's office."

Nhan admitted to being a member of Bloc 8406 and a spokeswoman for the illegal Vietnam Progression Party, adding: "The court is wrong. I am grown up and I am not insane. I have the right to debate."

A number of activists have recently been jailed on similar charges.

A court in Hue in late March sentenced dissident Catholic priest Nguyen Van Ly to eight years in jail and also imprisoned two co-accused.

On Thursday a Ho Chi Minh City court jailed a medical doctor, a journalist and a lawyer for three to five years, also for spreading propaganda.

Next Tuesday Tran Quoc Hien, a spokesman for the banned United Workers and Farmers' Association as well as being a Bloc 8406 member, faces court in Ho Chi Minh City on charges of defaming the state and disrupting security.