The six world powers preparing for talks with Iran are trying to agree a unified stance in Vienna. A meeting of the UN nuclear watchdog was adjourned for a day on Wednesday to allow diplomats more time for consultations. The six countries are divided on how tough they should be on Iran. Meanwhile IAEA experts have reportedly raised concerns about an Iranian military site, amid speculation of possible clean-up activities there. Satellite images of the Parchin military site suggest trucks and earth-moving equipment are being used, possibly to clear up traces of nuclear tests, diplomats have told the Associated Press. Iran claims that its nuclear programme is purely peaceful, but Western countries and Israel fear that it is developing nuclear weapons. The IAEA has previously said that it suspects the Parchin site may be being used for nuclear weapons related testing. Diplomats from the US, Britain, France, Germany, Russia and China are preparing to hold talks with Iran. Russia and China want a milder line than the Western nations, to foster a constructive atmosphere. Iran suggested on Monday that it would be prepared to grant UN weapon inspectors access to Parchin in the future. The complex, south of Tehran, is dedicated to the research, development and production of ammunition, rockets and explosives. IAEA inspectors last visited Parchin in 2005. In February they were turned away despite \"intensive efforts\".