The British foreign secretary says the government of Myanmar, also known as Burma, has vowed to free more political prisoners.
William Hague made the comments after meeting his Burmese counterpart Wunna Maung Lwin during the first visit to Burma by a British foreign secretary for 55 years.
The Burmese minister also promised that changes there were "irreversible".
However, the BBC reports that in a later interview the Minister did not use the word "political" when referring to prisoners, saying Myanmar did not acknowledge there were political detainees.
During his visit, Mr Hague will meet the president and the opposition leader Aung San Suu Kyi.
The British minister's visit is the latest in a series by high-profile diplomats seeking to engage the new government and try to encourage the first signs of reform.
Burma's first elections in 20 years took place in 2010 and brought in a nominally civilian government,
Since then the new administration has freed a number of political prisoners, including Ms Suu Kyi and begun a process of dialogue.
In December, the United States Secretary of State, Hillary Clinton, visited the country, in what was seen as an endorsement of the reform process - although Western observers say much more is needed.
Between 600 and 1,000 journalists, dissidents and monks who led anti-government protests in 2007 are thought to remain behind bars.