Most were members of ethnic minorities, said Ye Aung, who sits on the government's political prisoner scrutiny committee, but the list also included two grandchildren of former dictator Gen. Ne Win.
Both have been on death row since 2002 for allegedly attempting to stage a coup against the then-military regime of senior Gen. Than Shwe.
The continued detention of prisoners of conscience in Myanmar has been a concern of the United States and other Western nations, which want to promote the country's transition to full democracy following a half-century of brutal military rule.
Ye Aung, himself a former prisoner, said after today's announcement that at least 60 political prisoners remain in jail.
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Dozens of those released today had been charged under Section 18 of the Peaceful Assembly Law for staging protests without getting prior permission, he said.
Well-known activist Naw Ohn Hla, who was handed a two-year sentence in August for causing public panic, was another of the more prominent inmates released under today's deal.
During his visit to France in July, Thein Sein pledged that his government will free all political prisoners by the end of the year.