Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. Major Powers Decline Iran's Invitation to View Nuclear Sites VOA News 15 January 2011 Exterior of the Arak heavy water production facility in Arak, Iran, 360 kms southwest of Tehran (2004 file photo) Photo: AP Exterior of the Arak heavy water production facility in Arak, Iran, 360 kms southwest of Tehran (2004 file photo) Several international envoys are set to tour Iranian nuclear facilities, but key powers have declined Tehran's invitation to take part. Diplomats say China, Russia and the European Union are not participating in the tour on Saturday and Sunday.  The United States was not invited. The EU declined the invitation, saying inspectors from the International Atomic Energy Agency are the ones who should have access to the Iran's nuclear sites. Authorities say at least five countries - Algeria, Cuba, Egypt, Syria, and Venezuela - have accepted the invitation. Iran's unusual invitation comes ahead of a round of talks in Turkey next week about Tehran's atomic program. Britain, China, France, Russia, the U.S., and Germany will meet with Iran in Istanbul. Western powers suspect Iran wants to use its uranium enrichment activities to build a nuclear bomb. Tehran has denied the charge, insisting its program is a peaceful effort to produce nuclear energy. .