HO CHI MINH CITY, Vietnam— Vietnam will put a leading human rights lawyer and three other democracy activists on trial Wednesday, accusing them of a plot to overthrow the nation's communist government, which regards the advocacy of political pluralism as treason.

The four are accused of collaborating online with foreigners to promote democracy and of joining the Democratic Party of Vietnam, which, like all political parties, is outlawed in the single-party state.

They have been charged with "carrying out activities aimed at overthrowing the people's administration." The charge carries a maximum sentence of death.

The trial comes during one of Vietnam's periodic crackdowns against dissent. Some observers have speculated that the latest crackdown is the result of jockeying among political factions in advance of next year's Communist Party congress, which takes place every five years.

It is virtually unheard of for political defendants to be acquitted in Vietnam. The main issue to be determined at trial involves the length of the sentence.

One defendant is one of Vietnam's best-known lawyers, Le Cong Dinh, a U.S.-trained attorney and former vice chairman of the Ho Chi Minh City bar association. In addition to handling high-profile human rights cases, he once represented Vietnamese fish farmers fighting an unfair trade complaint brought by U.S. catfish growers.

During closing arguments at a 2007 human rights trial in Hanoi, Dinh, 41, made a highly unusual public plea for freedom of expression.

Dinh, who studied law at Tulane University on a Fulbright scholarship, is accused of going to Bangkok to attend a seminar on nonviolent political change organized by Viet Tan, an international pro-democracy network with members inside and outside Vietnam. Authorities say they also found a draft of a new constitution for Vietnam when they raided Dinh's Ho Chi Minh City law office in June.

Vietnam's government considers Viet Tan a terrorist organization, but U.S. officials say there is no evidence to support that view.

According to reports in Vietnam's state-controlled media, prosecutors have said the charges against Dinh constitute a "particularly serious violation of national security."

On the eve of the trial, Viet Tan issued a statement condemning what it called the "arbitrary charges" against Dinh and other democracy activists.

"The people of Vietnam have the right to discuss and advocate for the political system that best serves them," the statement said. "Viet Tan is committed to empowering Vietnamese to effect social change through peaceful, nonviolent means."

The other defendants are Nguyen Tien Trung, 26, who organized a pro-democracy student group while studying in France; and Tran Huynh Duy Thuc, 43, and Le Thang Long, 42, Internet entrepreneurs from Ho Chi Minh City and Hanoi, respectively.

Foreign reporters and diplomats will not be allowed to enter the courtroom, but will watch the two-day trial on closed-circuit television in a separate room at the Ho Chi Minh City People's Court. They are prohibited from bringing mobile phones, still cameras or video cameras.

In recent months, Vietnam has also arrested several bloggers and blocked the popular social networking site Facebook.

Last month, authorities convicted democracy advocate Tran Anh Kim of subversion and sentenced him to 5.5 years in prison for violating Article 79. In October, nine others were convicted of violating Article 88, a lesser charge that prohibits spreading progaganda against the state. (AP)