Two Thailand-based groups raised such charges earlier this year, which the military-led Burmese government has denied.
Officials here say they consider rape charges against the Burmese military personnel to be credible and they are calling for an investigation of the allegations by the United Nations and its special rapporteur on human rights in Burma, Paulo Sergio Pinheiro.
The issue surfaced in June of this year when two Thailand-based groups the Shan Human Rights Foundation and the Shan Women's Action Network issued reports alleging the rape by army troops of more than 600 women and girls in Burma's eastern Shan state.
The Burmese government denounced the charges as a fabrication. But State Department officials say diplomats from the U.S. consulate in the Thai city of Chiang Mai, sent to the Burmese border area in August, were able to locate many victims whose stories were similar to those documented in the reports.
A statement by the State Department's Bureau of Democracy, Human Rights and Labor said the U.S. diplomats interviewed 12 women who said they had been gang-raped by Burmese soldiers over the last five years including a 13-year-old girl who said she had been raped in June.
Most of the victims, who had recently arrived in Thailand, were said to have been "severely traumatized" by their experience and had described similar incidents of rape against relatives and friends, some of whom had died in the attacks.
Though describing the testimony was "anecdotal," the State Department human rights bureau said there was a "consistency" in the accounts given by differing groups of women in three different locations.
It said the U.S. government is "appalled" by the reports and vehemently condemns rape and all other forms of sexual violence against civilians.
The United States, it said, has expressed "deep concern" to Burmese authorities on several occasions urging them to investigate fully and to "appropriately" punish those guilty of such "heinous crimes."
Burmese officials were said to have proposed an investigation by the International Committee for the Red Cross, but the Geneva-based organization said it could not do so because of the confidential nature of its operating procedures.
A State Department spokeswoman said Thursday the United States continues to call for an international inquiry and "fully supports" efforts by Mr. Pinheiro the UN rapporteur and former top Brazilian human rights official to organize such an investigation.