Vietnam has released one of its best-known dissidents from prison, two weeks before its president is to make a historic visit to the United States, an official said Sunday.

Nguyen Vu Binh, 39, was released from Nam Ha prison on Saturday under a presidential amnesty, said Pham Hong Canh, deputy director of the prison in Ha Nam province, about 45 miles south of Hanoi.

Binh, a former journalist, is one of Vietnam's first "cyber-dissidents," a government critic who used the Internet to spread his pro-democracy views. In late 2003, he was convicted of spying and sentenced to seven years in prison and three years of house arrest.

The court said he had committed espionage by gathering anti-government information and documents for overseas "reactionary organizations."

Binh's early release comes as Washington has grown increasingly concerned about the arrest and jailing of a number of dissidents in communist Vietnam.

Also, President Nguyen Minh Triet is making a June 22 visit to the United States, the first by a Vietnamese president.

After the White House formally invited Triet to Washington, Vietnamese Vice Foreign Minister Le Van Bang announced last week that Hanoi would release three dissidents before the president's trip. He did not say which prisoners would be released.

In recent months, Vietnam has arrested several dissidents, including Catholic priest Thadeus Nguyen Van Ly, who received an 8-year prison sentence in March. As the arrests have mounted, complaints from Washington have grown more urgent.

President Bush recently met at the White House with four Vietnamese-American pro-democracy activists, including one who had been held in a Vietnamese prison.

Binh was arrested in September 2002 for writing an article that circulated on the Internet criticizing a border agreement between Vietnam and China. A month earlier, he joined 20 others in signing a petition to government leaders demanding legal reforms to protect human rights and establish an independent anti-corruption body. That same year, he also submitted written testimony to the U.S. Congress criticizing Vietnam's human rights record.

Binh left his job at Tap Chi Cong San (Journal of Communism) in 2001, after applying to form an independent opposition party. The Communist Party, Vietnam's only political party, strictly forbids any calls for a multiparty system.