Washington  - US President George W Bush said Tuesday he was "deeply troubled" by the decision of Myanmar's ruling junta to extend the detention of leading Democratic activist Aung San Suu Kyi and called for the immediate release of all political prisoners.

"The United States calls upon the regime to release all political prisoners in Burma and begin a genuine dialogue with Aung San Suu Kyi," Bush said in a statement.

Suu Kyi has been under house arrest since 2003 and has become the leading figure of the drive for democracy in Myanmar, which is also known as Burma.

The junta announced Tuesday her detention would be extended for an additional six months.

Since returning to the country in 1988, she has spent 12 years under house arrest.

The latest extension of her open-ended detention came on the 18th anniversary of the landslide election of Suu Kyi's National League for Democracy (NLD) in Myanmar's last general election. The junta refused to recognize those election results.

Suu Kyi is a Nobel Peace Prize winner. (dpa)