The girl from near Minsk, whose date of birth has been given as 1991, is part of a group of 25 Belarusian young people spending their summer holiday in California, who were due to return home on Tuesday. The Belarusian ministry did not clarify why the host family is holding the girl.
Charge d'Affaires Jonathan Moore, the top U.S. representative in Belarus, told reporters in Minsk after visiting the Foreign Ministry: "The embassy and the U.S. State Department are working closely with the Belarusian side to resolve this issue" and ensure the girl is returned to Belarus "as soon as possible."
The United States has not had an ambassador in Minsk since the envoy was expelled in March over sanctions against Belarus. The Belarusian Foreign Ministry also recalled its own ambassador from Washington.
The alarm was raised on Tuesday when the remaining 24 Belarusian teenagers met at San Francisco International Airport for their return flight to Minsk, but the girl failed to appear. Return flights for the rest of the group were also postponed.
A Belarusian Foreign Ministry spokesman told RIA Novosti that Belarusian Charge d'Affaires in Washington Oleg Kravchenko had discussed the issue at the State Department, and demanded that the U.S. ensure that the children are returned to Belarus as soon as possible.
In 2006, an Italian host family kept a Belarusian girl for three weeks, saying she had been treated badly at her orphanage. The girl was later returned to her home country.