Myanmar freed comedian and government critic Zarganar as it began releasing 6,300 convicts in a liberalizing move Wednesday, but kept several key political detainees behind bars, dampening hopes for a broader amnesty.

Relatives of convicts gathered expectantly at prisons around the country and held emotional reunions with those released, a day after the country's new civilian president issued an amnesty for inmates _ many of them ordinary criminals _ but without disclosing any names.

It was not clear how many of the country's estimated 2,000 political detainees were included in the amnesty. Relatives of some of them confirmed their release, while others said they were told by prison officials that their loved ones were not among those to be freed.

"The freedom of each individual is invaluable, but I wish that all political prisoners would be released," said Myanmar's most prominent pro-democracy campaigner and Nobel peace laureate Aung San Suu Kyi.

Suu Kyi's National League for Democracy confirmed the release of 155 political detainees, including members of the party, spokesman Nyan Win said. But others may have not yet contacted anyone.

A major release of political detainees has been eagerly awaited by Myanmar's opposition, as well as foreign governments and the U.N., as a gesture toward liberalization by the elected government after decades of harsh military rule.

A failure to release a significant number could hamper the country's efforts to burnish its human rights record and win a lifting of Western economic and political sanctions.

President Thein Sein, a retired senior army officer who took office at the head of an elected government in March, has launched a series of economic reforms and eased limits on freedom of speech by relaxing censorship and unblocking banned websites.

He also has started a dialogue with Suu Kyi, made calls for peace with ethnic minority rebel groups and suspending a controversial China-backed hydropower dam project after a public outcry.

One of the most prominent figures to be freed was comedian and activist Zarganar, who was serving a 35-year sentence in Myitkyina prison in northernmost Kachin State.

Zarganar was detained in 2008 after giving interviews to foreign media criticizing the former military rulers for being slow to respond to Cyclone Nargis, which left nearly 140,000 people dead or missing. He was convicted of causing public alarm and illegally giving information to the press.

"I am not happy at all, as none of my 14 so-called political prisoner friends from Myitkyina prison are among those freed today," he told The Associated Press by phone as he waited to board a plane to Yangon.

"I will be happy and I will thank the government only when all of my friends are freed," he said.

Relatives said several top members of some of the country's ethnic minority political parties were also among those freed.

However, the sister of famous former student leader Min Ko Naing said she was told he was not on the list of those to be freed.

"We are used to these ups and downs," Kyi Kyi Nyunt said.

Min Ko Naing has been serving a 65-year sentence at a prison in Shan State in northeastern Myanmar since 2008 for staging a street protest against a massive fuel price hike. He was arrested in August 2007 along with other well-known former students who were previously jailed after being at the forefront of a failed pro-democracy uprising in 1988.

At least one of his "'88 Generation" comrades, Ko Htay Kywe, also was not being released, according to his brother-in-law, Phyo Min Thein.

The United States, which has been seeking ways to re-engage with Myanmar, has said it wants all political detainees released. State Department spokeswoman Victoria Nuland said Tuesday that the U.S. would be keeping a close eye on who is released under the amnesty.

Washington has long isolated Myanmar with political and economic sanctions because of the former junta's failure to hand power to a democratically elected government and its poor human rights record.

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Associated Press writer Matthew Pennington in Washington contributed to this report.