BANGKOK (AP) — Tin Oo, one of the closest associates of Myanmar’s ousted leader Aung San Suu Kyi as well as a co-founder of her National League for Democracy party, has died. He was 97.

Tin Oo died Saturday morning at Yangon General Hospital, said Moh Khan, a charity worker, citing a member of his family. Charity workers in Myanmar handle funeral arrangements.

Moh Khan said Tin Oo had been hospitalized at Yangon General Hospital on Wednesday due to difficulty urinating and other health problems, including weakness. His cause of death was not immediately announced.

Tin Oo was respected by many of his party's members for his outspokenness and courage as he shared many of Suu Kyi’s travails.

In 1988, Tin Oo helped found the National League for Democracy with Suu Kyi after a failed revolt against military rule. He became vice chairman, then chairman of the new party.

But when the military cracked down the following year, he was put under house arrest, as was Suu Kyi. Similar to her, he spent 14 of the next 21 years under house arrest or in prison before he was released ahead of the 2010 general election. The party had won a 1990 election, but the results were annulled by the ruling military, which launched a crackdown on its opponents.

In 2003, in one of the intermittent periods when he and Suu Kyi were at liberty before their 2010 release, they had the harrowing experience of being ambushed on a country road in upper Myanmar by a mob widely believed to have been assembled by an element of the military. The incident occurred as the party leaders were making a political tour and attracting large crowds of supporters.

The two leaders managed an escape, though dozens in their entourage were apparently killed in the attack, details of which remain murky. Despite being the targets, Suu Kyi and Tin Oo were detained in prison and then house arrest again after the incident.

When the party was allowed to fully resume political activities, Tin Oo served as its senior leader and patron. He was often seen in public rallies, and he helped campaign with Suu Kyi for the 2015 election, which the party won by a landslide.

“He endured with dignity the various house arrest and prison terms, and detentions imposed on him,” Moe Thuzar, Senior Fellow and coordinator of the Myanmar Studies Program at Singapore's ISEAS-Yusof Ishak Institute said in an email interview.

“His sense of loyalty — to principles, to persons who he believed could uphold and continue the pursuit of this principles — was also evident in his unswerving support for the party he co-founded.”

Because the constitution enacted under military rule contained a clause effectively barring Suu Kyi from becoming president on the grounds that she was married to a foreigner — British academic Michael Aris — there had been speculation that Tin Oo might take the position.

He declared he wasn't interested, saying Suu Kyi should have the job.

“I never want to be president. I want to help her as much as I can,” he told journalists. Htin Kyaw, a politician and scholar, ended up as president, while Suu Kyi took the newly created post of state counselor, the equivalent of prime minister with overall authority over government.

Suu Kyi’s government was ousted by the army in 2021 after winning a second term in the 2020 election. Suu Kyi was arrested and tried on a series of charges that were widely seen as trumped up for political reasons to keep her locked up. Tin Oo was not arrested and was allowed instead to stay quietly at his Yangon home.

Tin Oo’s background was unusual for a senior politician opposed to army rule, as he joined the National League for Democracy after a high profile military career.

He had been Myanmar's fourth commander-in-chief of the armed forces between 1974 and 1976 under the government of the late dictator Gen. Ne Win. A year after his retirement, he was imprisoned for allegedly withholding information about a failed coup against Ne Win, but was released in 1980 under an amnesty. Some scholars believe he was purged because his popularity threatened Ne Win's grip on power.

Tin Oo displayed no inclination to reconcile with the military in which he once served, though they made several overtures.

Nearly a year after the 2021 army takeover, Senior Gen. Min Aung Hlaing, the head of the military government, paid a visit to Tin Oo at his home in Yangon and inquired about his health.

In June last year, a Buddhist monk with close links to the army visited and suggested to him that Suu Kyi should retire from politics and get involved in working for peace. The army's seizure of power spurred widespread armed resistance, which has since reached the intensity of a civil war.

A week after the monk's visit, Tin Oo's family hung a sign on their property's front fence declaring “No Visitors Allowed."