While he cannot verify that Iran’s nuclear programme is entirely peaceful, the head of the UN’s nuclear watchdog says he has found no proof of efforts to build atomic weapons. IAEA chief Mohammed El Baradei has been meeting top officials in Tehran to try to convince Iran to suspend its uranium enrichment and resume negotiations with the international community.It follows a triumphant declaration by president Mahmoud Ahmadinejad on Tuesday when he said his country had enriched uranium at a level of concentration high enough to operate a nuclear power plant. Along with other Western nations, Washington accuses Tehran of using its civilian nuclear programme as a cover to build weapons. While it says it wants to find a diplomatic solution, the US has left the military option open. In a new development, China has said it plans to send a senior envoy on arms control to Iran and Russia to try to defuse the nuclear standoff. Tehran says its program is for peaceful purposes only. Experts believe it could take years for Iran to produce enough enriched uranium for a single nuclear bomb. El Baradei is to report back the UN Security Council at the end of the month.