HANOI, Vietnam--The US Embassy in Vietnam expressed deep concern Tuesday about the arrest of a prominent lawyer known for his pro-democracy writings and defense of human rights activists.

Le Cong Dinh, 41, was arrested Saturday at his home in Ho Chi Minh City and accused of violating Article 88 of Vietnam's criminal code, which prohibits distributing information harmful to the government.

The US Embassy issued a statement calling for Dinh's immediate release.

"No individual should be arrested for expressing the right to free speech, and no lawyer should be punished because of the individuals they choose to counsel," the statement said.

According to accounts in communist Vietnam's state-controlled media, authorities believe Dinh "colluded with domestic and foreign reactionaries" bent on "sabotaging" the state and overthrowing the government.

Dinh, one of Vietnam's most high-profile attorneys, came to prominence several years ago when he defended Vietnamese catfish farmers in a trade dispute with US fishermen.

He also represented two human rights attorneys, Nguyen Van Dai and Le Thi Cong Nhan, who were convicted and jailed by the government in 2007 for promoting democracy.

In his defense of the pair, he made a strikingly direct plea for free expression, highly unusual in a country where the government tightly controls public speech.

Dinh has argued it was wrong to accuse those who promote free speech of undermining the state.