British Foreign Secretary William Hague says talks set to open in Geneva on Iran's nuclear drive are a "historic opportunity".
Hague told reporters during a visit to Istanbul on Wednesday that it is too early to say how the negotiations starting later on Wednesday between Iran and six world powers will go.
But he says a deal is on the table that will be in the interest of all nations, including countries across the Middle East.
"The differences that remain between the parties are narrow and I believe they can be bridged through political will and commitment," he said at a joint press conference with Turkish Foreign Minister Ahmet Davutoglu.
"It's an historic opportunity to build agreement on how to curb nuclear proliferation in the Middle East and potentially to set up relations with Iran on a different path."
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Britain is a member of the so-called P5+1 which also includes fellow permanent UN Security Council members China, France, Russia and the United States, and held a first round of negotiations with Iran which wrapped up 10 days ago.
Hague described those talks as "very constructive", saying they paved the way for a potential "first stage deal" between the two sides.
Hague declined to be drawn on comments by Iran's supreme leader Ayatollah Ali Khamenei that the Islamic republic's arch foe Israel was "doomed to collapse", saying it was the "substance" of the Geneva talks that mattered.
"It is the best chance for a long time to make progress on one of the greatest problems in foreign policy and we should all be conscious of that".
Davutoglu, who is due to visit Iran next week in a sign of warming ties with Turkey's eastern neighbour, says his government is "ready to do whatever is needed" for the nuclear negotiations to be concluded successfully as soon as possible.
Hague was in Istanbul to mark the 10th anniversary of bomb attacks in the city against the British consulate and a British bank in 2003 that killed 63 people, including the consul.
