YANGON (Reuters) - Myanmar's president announced an amnesty on Tuesday for about 100 prisoners, a senior official said, 56 of whom were confirmed as political detainees by a group monitoring activists held in the country's jails.
The release is the latest in a series of amnesties decided by reformist President Thein Sein and came a day after the European Union lifted all sanctions on Myanmar excluding an arms embargo.
Bo Kyi, of the Assistance Association for Political Prisoners (AAPP), told Reuters the group had confirmed the release of 56 political prisoners from five jails. According to AAPP, 176 remain in detention.
More than 800 political prisoners were freed in amnesties between May 2011 and November 2012.
In Washington, State Department deputy spokesman Patrick Ventrell urged the government to release all political prisoners.
"We welcome and encourage the unconditional release of all prisoners, but we do note that they've released about 50 today," he told reporters.
Previous releases of prisoners of conscience, as they are often known, coincided with reviews of Western sanctions or high-level visits, such as that by Thein Sein to Washington last September and President Barack Obama's landmark trip to Myanmar two months later.
"At key international moments the government releases a few political prisoners instead of releasing them all immediately," said Mark Farmaner, director of Burma Campaign UK.
"Almost all the laws used to put the political prisoners in jail are still in place."
The EU's decision to lift sanctions was criticised by rights groups for ignoring Myanmar's continuing human rights abuses, including the imprisonment of political activists and the persecution of Rohingya Muslims in western Myanmar's Rakhine State.
The State Department's Ventrell declined to comment on the EU move, and repeated U.S. statements of concern about the treatment of Myanmar's ethnic minorities.
"We have taken some measures to authorize the export of U.S. financial services to offer new U.S. investment, but we have a calibrated policy that includes sanctions authority and leaves them in place as a means to encourage continued progress on reforms," he said.
"Some of the policies are still in place if - if we need to use them," added Ventrell.
Human Rights Watch released a report the same day sanctions were lifted accusing state authorities of the ethnic cleansing of Rohingya Muslims after violence broke out in June and October last year, leaving at least 125,000 people displaced and 211 people dead.
Writing by Paul Carsten; Editing by Nick Macfie and Philip Barbara