Burmese opposition party officials say five activists have been sentenced to prison for participating in a silent protest to mark the 20th anniversary of a brutally crushed uprising.

National League for Democracy officials say the five were sentenced to two and half years in prison for participating in the rally on August 8.

The NLD activists and 43 others held a peaceful march in the town of Taunggok.  The others were later released.

The NLD says the five were charged with unlawful assembly and public mischief and not given any chance to defend themselves at the trial.

On August 8, 1988, government forces violently crushed a mass protest demanding an end to the country's military dictatorship.

The 1988 uprising brought down longtime military ruler Ne Win, but the military eventually regained control.

Burma's ruling junta allowed elections two years later, but refused to recognize the results when the NLD won the race.

The sentencing of the five activists comes days before United Nations special envoy Ibrahim Gambari is scheduled for a return visit to Burma.

The U.N. secretary-general's envoy will arrive in Rangoon on Monday for his fourth visit over the past year. Gambari is trying to persuade Burma's military leaders to open up a dialogue with opposition parties.

Some information for this report was provided by AP and Reuters.