Win Tin died of renal failure in a hospital in Yangon, Myanmar - also known as Burma. He had been admitted on March 12 with respiratory problems and kidney malfunction.

"He was a great pillar of strength. His demise at this important political juncture of transition is a great loss not only to the NLD but also to the country. We are deeply saddened," said Nyan Win, a spokesman for the NLD.

Win Tin, a former newspaper editor, was a close friend and supporter of Nobel Peace laureate Aung San Suu Kyi. The two activists founded the NLD in 1988.

In 1989, when Suu Kyi was placed under house arrest, Win Tin was also arrested and sent to Insein prison, where he served 19 years. While in prison, he received several international press freedom awards.

His sentence was extended twice for various reasons, the second time for writing a letter to the United Nations. He was freed as part of a general amnesty of prisoners in 2008.

Win Tin was one of the few party members who dared to be critical of Suu Kyi. In recent months, he had chided her for her conciliatory stance towards the military. Despite their differences, Win Tin respected Suu Kyi for her commitment for democracy. Suu Kyi had also gone to see him several times in hospital after she had returned froma recent trip to Germany and France.

Mayanmar's current government is led by the pro-military Union Solidarity and Development Party, which won the 2010 general election that was boycotted by the NLD. The military also controls 25 percent of parliament.

ng/hc (AP, dpa, AFP)