Police in Rangoon, Burma's largest city, kept close watch Saturday outside the headquarters of Aung San Suu Kyi's pro-democracy party, as it celebrated its 20th anniversary.

Plainclothes officers took pictures of people arriving for the ceremony, attended by at least 200 members of the National League for Democracy, as well as foreign diplomats.

The ceremony was also a homecoming for prominent journalist Win Tin, who was released from prison earlier this week after 19 years behind bars.  He is Burma's longest-held political prisoner.

The NLD released a statement calling for the ruling generals to release all political prisoners, including Aung San Suu Kyi, who has spent 13 of the last 19 years under house arrest.

The NLD was founded in 1988, after the military crushed a pro-democracy uprising in Burma.

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