The United States again called on Burmese military authorities Friday to release detained opposition leader Aung San Suu Kyi and take "immediate" steps toward forming a broad-based democratic government. The Bush administration has been dismissive of the Burmese junta's convening of a constitutional convention boycotted by the opposition.

The U.S. appeal came in a statement marking the May 30 anniversary of the attack outside Rangoon last year on a motorcade carrying Aung San Suu Kyi. Dozens of people were reportedly killed or wounded in the violence that also left the democracy leader and other key members of her National League for Democracy (NLD) party under detention.

State Department spokesman Richard Boucher called it a "brutal attack by government-affiliated thugs" on Ms. Aung San Suu Kyi and her supporters, and said that in the year that has elapsed since then there has been no progress toward a national accord in Burma.

"Now, one year later, the people of Burma are no closer to reconciliation or accountability for human rights abuses," said Mr. Boucher. "This month also marks the 14th anniversary of the 1990 elections, which were won overwhelmingly by the National League for Democracy, and the military junta has never recognized the results of those elections."

Mr. Boucher said that despite calls from the international community, the Burmese leadership has not accounted fully for the dead and wounded from the motorcade incident, and Aung San Suu Kyi and her fellow party senior leader Tin Oo remain under house arrest.

He renewed U.S. criticism of the national convention the Rangoon government convened this month under its so-called democracy "road map," saying it prohibits a free exchange of views and does not include the NLD or the United Nationalities Alliance, a group of ethnic parties that also took part in the 1990 election.

Ms. Aung San Suu Kyi, who won the Nobel Peace Prize for her democracy efforts, has been under varying forms of detention most of the time since 1990. The State Department urged the junta to release her, Tin Oo, and the more than 1,000 other political prisoners it holds, and to undertake a "substantive" dialogue with the opposition.