HANOI (AFP) - A Vietnamese lawyer was arrested on Wednesday (Dec 16) on anti-state charges, police said, a week after he was brutally beaten by thugs after leading a training forum for rights defenders in the communist country.

Nguyen Van Dai, 47, was taken into custody for "conducting propaganda against the state of the Socialist Republic of Vietnam," according to a statement posted on the Ministry of Public Security's website.

His Hanoi house was searched and his case is now under investigation, the statement said, without giving further details.

Dai has previously spent four years in prison for the same charges. He was released in March 2011 when his term ended. His legal licence has been revoked, so he is no longer able to practice law.

Dai has become a high-profile dissident in Vietnam, and his thoughtful critiques of the country's communist leadership and policies receive widespread attention on dissident blogs and social media.

A year before he was jailed in 2007, Dai founded the Vietnam Committee for Human Rights, and had often represented dissidents and protestors who were prosecuted by the government.

Last week, Dai and three colleagues were attacked by a group of around 20 stick-wielding men after they had led a training forum for 60 human rights defenders in central Vietnam, in what the UN High Commissioner for Human Rights said was an "alarming" incident.

UNHCR said the incident was the third violent attack on activists in Vietnam since September, and slammed the government for failing to investigate and prosecute the perpetrators.

In two other recent cases, lawyers and activists have been attacked "apparently in reprisal for their work on sensitive cases," UNHCR said in a statement, urging the government to investigate and take action.

Activists have claimed that plainclothes policemen were involved in the attacks.

Vietnam's Communist Party, which has run the unified country since 1975, is highly sensitive to any public criticism of its rule.

The one-party state is regularly denounced by rights groups and Western governments for its hardline stance on any issues concerning press freedom or human rights.

Vietnam bans private media and all newspapers and television channels are state-run.

In October, a former soldier turned democracy campaigner Tran Anh Kim, 66, was arrested for subversion, a charge on which he had previously been jailed for more than five years.

On Monday, Nguyen Viet Dung, 29, was jailed for 15 months for wearing the army uniform of the former South Vietnam regime at a protest in Hanoi.