BANGKOK — Myanmar freed a prominent dissident on Wednesday at the start of what state media said would be the release of 6,300 prisoners in a general amnesty that was expected to include a number of political prisoners.

The first dissident known to have been freed was a popular comedian known as Zarganar, who was imprisoned in 2008 for criticizing the government, according to reports from Myanmar.

The releases of political prisoners had been signaled by an open letter from the country’s new human rights body, which called on the government to free “prisoners of conscience,” a term that was a departure from the country’s longstanding position that all prisoners are common criminals.

The release of the country’s estimated 2,100 political prisoners has been a central demand of Western nations.