Russia’s foreign minister Sergei Lavrov says a military strike against Iran would be a “catastrophe”.

Lavrov also says any attack against Iran would result in large flows of refugees from Iran and would also “pour fuel on the fire of hidden Sunni-Shia confrontation that is already smouldering” and might prompt “a chain reaction”.

Iran’s foreign minister Ali Akbar Salehi told reporters that negotiations about where and when to hold talks on Iran’s nuclear programme were ongoing. However, the UK Foreign Office said there were no dates or concrete plans for talks as Tehran was “yet to demonstrate clearly that it is willing to respond to [EU foreign policy chief] Baroness Ashton’s letter and negotiate without preconditions”.

“Until it does so, the international community will only increase pressure on it through further peaceful and legitimate sanctions.”

Tensions between Iran and the West are increasing after reports that Tehran was producing 20 per cent enriched uranium at its Fordow plant were confirmed by the UN energy watchdog, the International Atomic Energy Agency (IAEA).