Correction: Earlier versions of this article incorrectly said that the last U.S. ambassador departed Rangoon in 1988. The last ambassador left in 1990. This version has been updated.

The Obama administration is preparing to send an ambassador to Burma for the first time in 24 years, Secretary of State Hillary Rodham Clinton said Friday in a further sign of the thaw in relations between the two countries.

The announcement of the step toward full diplomatic relations came one month after a visit by Clinton to the Southeast Asian country, which has begun liberalizing its political system after decades of military rule. The move coincided with the release by Burmese authorities of hundreds of political prisoners.

“We will start the process of exchanging ambassadors with Burma,” Clinton told reporters at a news conference. She said restoring full diplomatic representation would be a lengthy process that would “depend on continuing progress and reform.”

“But an American ambassador will help strengthen our efforts to support the historic and promising steps that are now unfolding,” she said.

The U.S. diplomatic mission in Rangoon has been headed by a charge d’affaires since 1990, when the United States recalled its ambassador to protest the government’s brutal crackdown on the country’s democratic opposition. Since then, U.S. administrations have imposed sanctions on Burma, also known as Myanmar, and criticized its record of repression, which has included jailing thousands of opposition figures and dissidents and tolerating the widespread practice of forced labor and human trafficking.

The country’s military junta, facing a growing economic crisis, revamped the constitution in 2008 and embarked on a series of economic and political reforms that have been enhanced under President Thein Sein, who took office in March. Clinton’s visit to Rangoon, the first by a U.S. secretary of state in half a century, was intended to encourage faster reform and pave the way for improving bilateral ties.

President Obama hailed Burma’s progress in a statement on Friday and praised the decision to release political prisoners, some of whom have spent decades behind bars. He also lauded the Thein Sein government’s recent announcement of new elections, set for April 1, and a new cease-fire agreement with Burma’s Karen ethnic minority.

Obama recalled a speech last fall during a presidential visit to Indonesia in which he spoke of “the flickers of progress that were emerging” in Burma.

“Today, that light burns a bit brighter, as prisoners are reunited with their families and people can see a democratic path forward,” Obama said.

A senior State Department official, who insisted on anonymity in discussing diplomatically sensitive events in Burma, said U.S. officials had confirmed that the releases had taken place across “a whole series of prisons across the country.” A total of 651 political prisoners had either been released or offered freedom under a presidential pardon, the official said, and the releases appeared to be free of restrictions or conditions.

“So far, everything that has been publicly reported by the government appears to be in alignment with what we are seeing on the ground,” the official said.

Burmese opposition leader Aung San Suu Kyi, released from house arrest in 2010, said this week that she plans to run for parliament in April. She has expressed cautious optimism about the reforms but also concerns that some in the military might not support them.