More than 8000 prisoners, including several prominent dissidents, are due to be released in Vietnam as part of an amnesty to mark the lunar New Year.
The prisoners are being released in time for the lunar New Year
Democracy advocate Nguyen Dan Que and Catholic priest Nguyen Van Ly are among at least four political prisoners due to be freed in the coming days.
Vietnam is frequently criticised abroad for its poor human rights record.
The campaign group Amnesty International welcomed the government's decision to release the dissidents.
"The Vietnamese authorities have at long last realised that locking up elderly men for decades, for doing nothing more than peacefully criticising government policy, is both a tragedy for those concerned and a stain on Vietnam's reputation," said Natalie Hill, Amnesty's deputy Asia director.
Vietnam regularly releases prisoners on national holidays and important anniversaries.
Another large amnesty is expected to be announced in April, to mark the 30th anniversary of the fall of the US-backed South Vietnamese regime.
Of more than 8,000 people being released for the lunar New Year (Tet) festivities, 33 are said to be foreigners - from the US, Australia, South Korea, Taiwan, China, Laos, Cambodia and Malaysia.
At least four of the others are political prisoners - named by Amnesty as Nguyen Dan Que, Father Nguyen Van Ly, Nguyen Dinh Huy ( the founder of a democracy movement in Ho Chi Minh ) and Huynh Van Ba (an outspoken Buddhist monk).
Nguyen Dan Que has been in and out of jail since 1978.
Vietnam is regularly criticised for political and religious intolerance
His latest arrest was in July 2003, days after he had written a series of internet articles criticising government curbs on journalists.
He was sentenced to 30 months in jail for "abusing democratic rights to infringe upon the interests of the state".
Father Ly, an outspoken Catholic priest, was sentenced to 15 years in prison in October 2001, charged with undermining national unity.
He had angered the authorities by sending a letter to the United States Commission on International Religious Freedom, urging Washington not to agree to bilateral trade unless Vietnam improved its human rights record.
His sentence was reduced to 10 years in 2003, and then to five years in June 2004, because officials are said to have noted his "good attitude and conduct" while in prison.
Vietnam denies charges that it represses human rights.
It permits the practice of six mainstream religions, but tightly controls their operation, including appointments of religious leaders.
Last year, the US State Department ranked Vietnam as one of the most repressive nations in the world in terms of religious freedom.