Transnistria, a strip of land between Moldova and Ukraine, broke away from the Soviet republic of Moldova in the 1990s. Most of its population are Russian and Ukrainian nationals.
"The international 5+2 format with the participation of all our foreign partners…is not working," Transnistrian Acting Foreign Minister Vitaly Ignatiev said at a press conference in Moscow.
According to Ignatiev, Moldova attributes its non-participation in the negotiations to an internal political crisis, which hit the country last September.
The 5+2 format negotiators include Russia, Moldova, Transnistria, Ukraine, the Organization for Security and Co-operation in Europe, as well as observers from the European Union and the United States.