Britain denied on Wednesday that negotiations were under way towards a new round of nuclear talks between Iran and Western powers, contradicting Iran's foreign minister.

There are no dates or concrete plans because Iran has yet to demonstrate clearly that it is willing to respond to (EU foreign policy chief) Baroness Ashton's letter and negotiate without preconditions, said a spokesman for the Foreign Office in London.

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

(Reporting by Estelle Shirbon, editing by Stephen Addison)