Iran and six world powers began drafting a comprehensive nuclear deal at their last talks in May and this will continue in the new round starting today, a senior US official said.
"Actually there was some drafting... At the last round," the official said. "A little bit of that was done the last time, and it was expected more will take place during this round."
While stressing that "significant" differences remain, the official indicated that progress was made at bilateral talks between the United States and Iran in Geneva last Monday and Tuesday.
"We not only understood each other better after those two days but I think we both can see places where we might be able to close the gaps," the official said.
"But this is, as you know, an agreement where nothing is agreed until everything is agreed, and no one is willing to say what they will agree to until they actually have to," she said.
"There is going to be a lot of dancing around for some time."
She also said that negotiators are "not having discussions" about extending a July 20 deadline, when a six-month interim deal between Iran and the five permanent members of the UN Security Council plus Germany expires.
The six powers want Tehran to scale back its nuclear activities, while Iran wants all UN and Western sanctions to be lifted.
This long hoped-for accord would aim to once and for all silence fears that Tehran might develop nuclear weapons, and avert a slide into international conflict.
