U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif are using their first full day of renewed overtime at nuclear talks to whittle away at disputes that have led to four extensions of the latest round.

All seven nations at the talks agreed to set a new target day of Monday for an accord after realizing that they could not wrap up the talks as they hoped to do by Friday.

Negotiators had originally hoped to come up with a deal by June 30. Kerry and Zarif met as talks entered their 15th straight day Saturday.

Any deal is meant to clamp long-term restrictions on Iranian nuclear programs that are technically adaptable to make weapons in exchange for sanctions relief for Tehran.