Hundreds of Burmese political prisoners walked free Friday, part of a mass amnesty that could signal more political reforms are on the way.

Officials and democratic activists said the 651 prisoners had been locked away under the rule of the country's military junta. But Burma's new military-backed government has been reaching out to the West and recently hosted both U.S. Secretary of State Hillary Clinton and British Foreign Secretary William Hague.

Hague on Friday said he welcomed the prisoner release, calling it a “further demonstration of the Burmese government's commitment to reform.”

Burmese state media said the detainees were freed under an amnesty ordered by President Thein Sein in order to foster national reconciliation.

Those freed included democracy activist Min Ko Naing – a key student leader of the failed 1988 uprising – and Shin Gambira, a well-known Buddhist monk who led street protests in 2007.

The military-backed government also released Shan ethnic minority leader Khun Htun Oo, who was serving a 93-year sentence on charges of treason, and former prime minister and intelligence chief Khin Nyunt.

Burmese researcher David Mathieson of Human Rights Watch told VOA that the amnesty represents a significant step on Burma's path towards democracy.

“You're talking about quite a comprehensive list of prominent political activists, journalists, labor activists, Buddhist monks and former members of the government. So this is really quite a significant release.”

Mathieson said he hopes those released will be able to play a part in the national political process ahead of highly anticipated by-elections scheduled for April 1.

“We're actually entering a very interesting phase in modern Burmese politics, and everyone released today certainly has a very prominent role to play in that.”

The amnesty comes a day after the Burmese government signed a cease-fire deal with the ethnic Karen rebel group.

Burma hopes the amnesty and the peace deal will help improve relations with the international community. The United States and European Union have repeatedly called for Burma's nominally civilian government to free all of its political prisoners. After Friday's release, it is unclear how many prisoners of conscience remain in Burmese jails.

Meanwhile, a leading congressional voice behind U.S. sanctions on Burma, Senator Mitch McConnell, says he will begin a three-day visit to the country on Sunday to assess political reforms. He plans to meet pro-democracy activist Aung San Suu Kyi and government officials in his first ever trip to Burma.

Another U.S. congressman, Representative Joe Crowley, is currently in Burma to encourage the government's reform efforts.