BRUSSELS (Reuters) - The European Unions executive said on Wednesday it was up to the UN nuclear watchdog to inspect Iranian atomic facilities, after Tehran invited EU envoys to tour the sites this month. The European Commission said it had yet to reply to the invitation sent to some ambassadors, including the EUs, accredited to the International Atomic Energy Agency in Vienna, weeks before a second round of talks between Iran and six world powers on its disputed nuclear ambitions. Iran invited the EU as well as China, Russia and others to visit, in a move that raised questions in the West as to whether it constituted a genuine step toward more nuclear transparency or a public relations stunt meant to divide major powers and buy time for further atomic advances. The West suspects Irans nuclear program is directed at developing bombs. Tehran says it is for peaceful energy only. The EU said inspections should be carried out by specialists from the International Atomic Energy Agency (IAEA), rather than ambassadors to the UN watchdog who were invited by Tehran. We havent answered the letter, a European Commission spokesman told a regular news briefing on Tuesday, after being asked whether the EU had accepted or rejected Tehrans offer.