On June 22, Britain urged Iran to show more flexibility in talks on its contested nuclear program as an end-of-June deadline looms after years of torturous negotiations with the West.

“There will need to be some more flexibility shown by our Iranian partners if we are going to reach a deal,” British Foreign Secretary Philip Hammond said.

“I think the serious negotiations are now getting underway and over the next week, I hope to start to see some progress,” Hammond said. “We are pushing hard to get there now.”

Hammond was speaking as he arrived for a meeting of European Union foreign ministers in Luxembourg where he will also hold talks with Iranian Foreign Minister Mohammad Javad Zarif.

EU diplomatic sources said over the weekend that Zarif would meet several of his EU counterparts on June 22, including Hammond, France’s Laurent Fabius, Germany’s Frank-Walter Steinmeier, and EU foreign affairs head Frederica Mogherini.

Fabius warned on June 20 that any deal with Iran had to be tough and verifiable to ensure no backsliding.

“We think that we must be extremely firm and that, if an agreement is to be reached, that agreement must be robust,” Fabius said at a joint news conference with Prime Minister Benjamin Netanyahu in Jerusalem.

“That means that it must be able to be verified,” Fabius added.

Iran and the P5+1 powers, which are Britain, China, France, Germany, Russia, and the United States, agreed in April on the main outlines of what would be a historic deal scaling down Tehran’s nuclear program.

The two sides, having missed a March 31 deadline, set a new date of June 30 to finalize the accord and negotiators have been meeting regularly in Vienna and elsewhere since then to hammer out a deal.

The West fears that Iran’s nuclear program has military objectives but Tehran insists that it is for purely peaceful energy development purposes.