The United States said Thursday that it was concerned that Burmese detained opposition leader Aung San Suu Kyi may not be retrieving food delivered to her home but has not been able to confirm such reports.

Suu Kyi’s supporters believe the Nobel Peace Prize laureate may be on a hunger strike to protest the military-run government’s refusal to hold talks on democratic reforms. They said Tuesday she has failed to retrieve food for nearly two weeks.

State Department spokesman Robert Wood told reporters that Suu Kyi and other political prisoners in the military-run country, also known as Burma, should be released.

Suu Kyi, who has been under house arrest for 13 of the past 19 years, relies on her National League for Democracy party’s food deliveries for sustenance. In 2003, there were reports that were never confirmed that Suu Kyi staged a hunger strike to protest her detention conditions.

Suu Kyi repeatedly canceled meetings with U.N. Special Envoy Ibrahim Gambari during his six-day visit to Burma that ended Saturday. Supporters have speculated that she has grown more frustrated with the U.N. failure to bring about change in the military-ruled nation.

Wood said in a statement that the U.S. is “deeply disappointed” that the Burma government failed to cooperate with Gambari. He did not mention Suu Kyi’s reported complaints with the U.N.

Wood called on Burmese generals to “live up to agreements made with U.N. representatives during prior trips. Improved relations between Burma and the international community depend on the Burmese regime taking concrete and sincere steps in this direction.”