New expert talks on Iran deal may start next week: US

Expert talks to resolve the toughest issues blocking a full Iran nuclear deal could begin next week as the countdown starts to a June 30 deadline, a US official has said.

Secretary of State John Kerry arrived late yesterday at Congress to brief skeptical House lawmakers about the outlines of a deal struck earlier this month in Lausanne.

He told reporters before the closed-door briefing open to all 435 House lawmakers that he wanted to go into "some detail because there have been a lot of ... Misrepresentations."

"We hope Congress will listen carefully and ask the questions that it wants, but also give us the space and time to be able to complete a very difficult task which has high stakes for our country," Kerry added.

He will also meet today with senators seeking to stave off new legislation aimed at ensuring Congress gets to approve any final deal, as well as imposing possible new sanctions on Iran.

Republican Senator Bob Corker, who has co-sponsored a draft bill to give Congress the power to review any final deal, said he may be garnering enough support to overcome any veto by President Barack Obama.

"I think things are moving our way," Corker told CNN.

"Let's let Congress weigh in on that, and if Congress doesn't believe this is an acceptable transaction, have the opportunity for a resolution of disapproval which would stop those sanctions from being lifted."

Kerry's lead negotiator Under Secretary Wendy Sherman was meanwhile already en route for Germany and a meeting of G7 countries.

Kerry will join the G7 foreign ministers meeting in Lubeck tomorrow, but on the sidelines Sherman will discuss with European political directors the next steps in the Iran negotiations following the April 2 breakthrough.

The framework hammered out in Lausanne after months of tough negotiations sets out the parameters for a final deal scaling back Iran's nuclear program.