YANGON, Myanmar ? Kyi Maung, a former army officer who became a leading member of Myanmar’s pro-democracy movement but later fell out with its leader, died Thursday. He was 85.

Kyi Maung died of a heart attack, his widow said.

Along with Aung San Suu Kyi, with whom he had a falling out, Kyi Maung was a founder in 1989 of the National League for Democracy, and as a party vice chairman played a prominent role in its activities. As result, he also spent several years in jail.

He was a victorious candidate for Parliament in a 1990 general election won by the NLD, and as a top party leader would probably have played a prominent role in the government had the military handed over power.

But the junta refused to allow Parliament to convene, and stepped up repression of the party, which continues to this day, with Suu Kyi under house arrest.

Popular for his straightforward manner and sense of humor, Kyi Maung was still widely admired after he left the party in 1997 because he did not switch his allegiance to the government.

His reason for leaving was never publicly revealed, though it was generally known that he had sharp differences with Suu Kyi.

Kyi Maung was an anti-government activist before the NLD was founded after massive pro-democracy demonstrations in 1988 that the military violently suppressed.

He served a total of seven years in prison under the regime of the late Gen. Ne Win, who ruled from 1962-88, and was jailed several times under the junta that succeeded him.