BAGHDAD (Reuters) - Iraq invited Russian parliamentarians on Thursday to visit presidential sites at the centre of a row between Baghdad and the United Nations, the Iraqi News Agency (INA) said. It said the invitation for the "field visits" was made by the speaker of Iraq's National Assembly Saadoun Hammadi. "The government of the United States says Iraq is producing and concealing biological and chemical weapons in the presidential sites," the agency quoted Hammadi as saying. "In order to reach the truth the Iraqi national assembly formally offers to the members of the Russian Duma council to visit the sites to inspect their contents." Iraq has barred U.N. weapons inspectors from entering the presidential sites, saying the inspections would violate its sovereignty. The United States and Britain have warned they could use military force to try to make Iraq back down. Iraq made a similar invitation to members of the U.S. Congress. Last week it hosted three lunches for Baghdad-based diplomats in presidential sites around the country.