PARIS (AFP) - France called on Sunday for tougher sanctions against Iran over its controversial nuclear programme. The time has come to seek firmer sanctions against Iran, Secretary of State for European Affairs Pierre Lellouche said on the French Jewish radio station Radio J. World powers object to Tehrans uranium enrichment programme, as the process can be used to produce fuel for a nuclear reactor or to make an atomic bomb. Iran insists it is enriching uranium for peaceful ends. UN Secretary-General Ban Ki-Moon on Sunday expressed strong concern over Iran, but said he had no details of any proposals for further sanctions. He said Iran must fully respect resolutions already passed on its nuclear programme by the United Nations Security Council, according to a French translation of Bans comments on television channel TV5. Lellouche recalled on Sunday that Iran has refused a UN-mediated offer to send its uranium stockpile to Russia and France to be refined for use in a medical reactor.