Ambassador Louis O'Neill, the head of the mission, said during a visit to the school that the building should be returned without further delay.
O'Neill was on a fact-finding trip to learn about the situation of six educational institutions in Transdniester that teach in Romanian, as required by the Moldovan Education Ministry.
The school was built by the government in Chisinau and was nearly finished when pro-Russian Transdniestrian militias seized it in the summer of 2004.