Brussels - Top diplomats from the so-called "5+1" group of world powers were to meet in Brussels on Friday to discuss how to respond to Iran's refusal to reach a nuclear deal, diplomats said Thursday.

Officials from the UN Security Council's five permanent members - Britain, China, France, Russia and the United States - plus Germany were to also hold talks with European Union foreign policy chief Javier Solana, spokeswoman Cristina Gallach told the German Press Agency dpa.

The meeting was to take place a day after Iranian President Mahmoud Ahmadinejad brushed off international warnings after rejecting a compromise deal on the country's controversial nuclear programme.

US President Barack Obama said earlier Thursday in Seoul that the US and its international allies would discuss "consequences," most likely in the form of tougher sanctions against Iran, after the Islamic state has not yet accepted a deal negotiated by the International Atomic Energy Agency (IAEA). (dpa)