GENEVA (Reuters) - A U.N. human rights watchdog called on Vietnam on Thursday to stop imprisoning activists and journalists for criticizing state policies and voiced concern at a “high number of death sentences and executions” imposed for lesser crimes after flawed trials.

The U.N. Human Rights Committee reviewed Vietnam’s record on upholding civil and political freedoms, marking the first time Hanoi has engaged with the independent experts since 2002.

Despite presiding over sweeping reforms and an increasingly market-oriented economy, the Communist Party of Vietnam tolerates little criticism.

Nguyen Khanh Ngoc, deputy justice minister, told the U.N. panel this month that Vietnam was working hard to protect human rights in its national development process.

“There has been a dramatic increase in crackdowns against human rights defenders,” panel member Marcia Kran told a news briefing.

“They have been harassed, attacked, they have been held in incommunicado pre-trial detention. Some have received lengthy prison sentences for charges under quite vague legal provisions, and they have been ill-treated in custody as well,” she said.

Some activists were exiled after serving partial prison terms, the panel said, citing Nguyen Ngoc Nhu Quynh, a blogger and environmental activist who adopted Mother Mushroom as a pen name.

Quynh was released last October after serving two years of a 10-year term, and arrived in the United States.

The U.N. panel called for a moratorium on Vietnam’s extensive use of the death penalty, including for drug-related and economic crimes, which it said do not meet the threshold of the most serious crimes under international law.

Domestic laws have provisions on national security crimes that “encompass legitimate activities, such as exercising the right to freedom of expression”, it said.

“The number and the identities of persons sentenced to death are kept secret by the authorities which means it is possible for dissidents to be targeted and sentenced to death without due process,” Kran said. “Others have died in custody.”

Panel member Christof Heyns cited public reports that 85 people were executed last year in Vietnam.