Human rights groups have welcomed the early release of a cyber dissident by Vietnam - but urged the government to stop restricting use of the internet.
Cyber cafes must monitor their customers' internet use
The Vietnamese authorities unexpectedly announced the release of Le Chi Quang, 34, on Monday.
He was jailed for four years in November 2002 for posting several essays on the internet critical of the communist government.
Rights groups say at least six other cyber dissidents remain in jail.
Amnesty International expressed "relief" at Quang's release.
"This young man, who suffers from ill health, should never have been arrested and imprisoned in the first place," Amnesty said.
The Vietnamese foreign ministry said Quang would have to serve out a three -year term of house arrest which was given at the time of his detention.
Qunag, a lawyer and computer teacher, had published comments critical of land and sea border agreements between Vietnam and China.
The Paris-based watchdog Reporters Without Borders (RSF) said Quang's release was an "encouraging first step" but called on Vietnam to show similar clemency towards the six other cyber dissidents still being held.
"We still expect Vietnam to stop censoring the internet and and stop imprisoning internet users just for expressing their views online," the group said.
Vietnam has introduced tough measure to monitor internet use. Internet cafe owners must keep records of all sites visited by their customers, including those deemed containing "bad and poisonous information", for 30 days.