Myanmar announced a mass prisoner amnesty Tuesday, raising hope for the imminent release of hundreds of political detainees in what would be a major sign of change in the authoritarian state.

More than 6,300 prisoners will be pardoned from Wednesday "on humanitarian grounds", state television announced, without saying whether political prisoners would be among them.

The fate of the country's estimated 2,000 political detainees, who include pro-democracy campaigners, journalists, monks and lawyers, has long been a top demand of Western nations that have imposed sanctions on Myanmar.

The announcement came just hours after a government-appointed human rights panel called for a pardon for the country's "prisoners of conscience".

The National Human Rights Commission said freeing detainees "who do not pose a threat to the stability of state" would allow them to participate in "nation-building", according to an official English-language newspaper.

It noted that UN Secretary General Ban Ki-moon and foreign governments were calling for "the release of what is referred to as 'prisoners of conscience'," in a rare official acknowledgement of their existence.

On Monday a government official, speaking on condition of anonymity, told AFP that political prisoners were expected to be freed within days.

Their release would be arguably the clearest sign yet of change under a new leadership that has reached out to critics including opposition leader Aung San Suu Kyi, freed in November after seven straight years of detention.

President Thein Sein, a former general and senior junta figure, has surprised critics by signalling a series of political reforms since taking power following a controversial election last November.

He has been applauded by international observers for holding direct talks with Suu Kyi, whose National League for Democracy (NLD) on Monday said it was "expecting" all political detainees to be released.

A top US official, Kurt Campbell, on Monday hailed recent developments in Myanmar, including what he described as "very consequential dialogue" between Suu Kyi and the leadership.

He hinted that concrete moves towards democracy by Myanmar could lead to an easing of sanctions.

"We will match their steps with comparable steps," he said.

The new regime, which came to power after controversial elections held a few days before Suu Kyi's release, appears keen to improve its image and in August held the first talks between her and Thein Sein, a former general.

Suu Kyi, whose party won 1990 election but was never allowed to take power, has said she believes Thein Sein genuinely wants to make reforms, but she cautioned it was too soon to say whether he would succeed.

The NLD boycotted last year's ballot, largely because of rules that would have forced it to expel imprisoned members. As a result it was delisted as a political party by the regime.