The Bush administration urged the Myanmar government on Thursday to free pro-democracy leader Aung San Suu Kyi (search) from house arrest, saying a failure to do so would represent "unacceptable backtracking."

A spokesman for Suu Kyi's political party had said Monday that the opposition leader had been told her house arrest would continue at least until September — word that White House spokesman Scott McClellan said was noted with "deep concern" in Washington.

"If true, this represents a return to a pattern of unacceptable backtracking on commitments the regime itself has made to move toward democracy and national reconciliation," McClellan said.

The Bush administration had believed the military government in Myanmar (search), also known as Burma, was moving in a more encouraging direction with the recent release of more than 9,000 prisoners, including a small number of political prisoners.

"But the continued detention of Aung San Suu Kyi seems to indicate this is not the case," McClellan said. "The generals in Rangoon must come to understand that they cannot indefinitely suppress the legitimate aspirations of the Burmese people and resist the worldwide march to freedom and democracy."

The junta came to power in 1988 when it crushed a pro-democracy uprising in which Suu Kyi had risen to prominence. It called elections in 1990 but refused to hand over power when Suu Kyi's party, the National League for Democracy (search), won overwhelmingly.

Suu Kyi, the 1991 Noble Peace Prize (search) winner, has been detained several times, the latest in May 2003 when she was taken into custody after her motorcade was attacked by a mob. After being held by the military, she was transferred to house arrest last September.