Prime Minister David Cameron has called on Iran to return to the negotiating table ready to talk seriously about international concerns over its nuclear programme.
Mr Cameron said recent talks between Iran and the E3+3 group - the UK, France, Germany, US, China and Russia - in Moscow had been "a missed opportunity".
Speaking after talks with Mexican President Felipe Calderon in Mexico City, Mr Cameron said: "We remain committed to reaching a diplomatic solution on Iran.
"Lack of progress at the talks in Moscow was a missed opportunity to address the serious concerns of the international community.
"The EU sanctions will kick in properly on July 1 and I hope that the Iranians will reconsider and return to the table willing to negotiate seriously."