The Iran Six, which brings together Russia, the United States, China, France, Britain and Germany, met in London at the level of political directors and welcomed the new direction of U.S. policy towards Iran, particularly Washington's decision "to join in any future meetings with representatives of the Islamic Republic of Iran."
"To that end, we shall ask Dr Javier Solana, the European Union's high representative for common foreign and security policy, to extend an invitation to the Iranian government to meet representatives of the E3+3 [Iran Six], so that together we may find a diplomatic solution to this critical issue," the participants said in a statement.
U.S. President Barack Obama said in March he expected steady progress in relations with Iran as he pursued a policy of greater engagement than his predecessor George Bush.
Iran is under three sets of relatively mild sanctions over its nuclear program, which it insists is purely civilian but the West, led by the United States and Israel, maintains is aimed at developing nuclear weapons.
The most recent UN Security Council resolution was passed in September last year. Although it did not include any new sanctions it called on Iran to fulfill its responsibilities under previous resolutions and IAEA commitments.