GENEVA -- Iranian and U.S. officials involved in talks in Geneva over Tehran's controversial nuclear program reported some progress but said a lot of work remained to secure a deal before the March 31 deadline.
Iranian Foreign Minister Mohammad Javad Zarif said on February 23 at the conclusion of two-days of talks that they were "useful, constructive, and serious" but that there is still a "long way" to go.
Zarif, who met directly with U.S. Secretary of State John Kerry during portions of the negotiations, said the talks would resume in Switzerland on March 2.
A senior U.S. administration official at the talks said "some progress" had been made and that the six world powers and Iran had been able to "sharpen up some of the tough issues" that need resolving.
U.S. Energy Secretary Ernest Moniz and Iranian nuclear chief Ali Akbar Salehi were also involved in the talks along with Helga Schmid, political director of the European Union's External Action Service.
The United States, Russia, China, Britain, France, and Germany are seeking an agreement with Tehran that would rein in Iran's nuclear program in exchange for relief from economic sanctions.
Tehran dismisses Western suspicions it is using its civilian nuclear program to also secretly develop nuclear weapons.
After missing two self-imposed deadlines last year, the six powers and Iran are seeking a political framework by the end of March and a full deal by June 30.
The Reuters news agency quoted a senior Iranian official as saying that both sides "are determined to resolve the remaining issues."
"Gaps still remain and the negotiators are trying hard to reach a common point," said the Iranian official, who described the atmosphere as "good but very serious".
A senior State Department official said the session would cover "virtually every topic," Reuters reported.
The 12-year-old dispute over Iran's nuclear program has added to tensions in the Middle East and prompted fears of a new war.
Iran says that its nuclear program is for purely peaceful purposes including power generation, but its enrichment of uranium and other activities have worried the West and the International Atomic Energy Agency (IAEA), the UN nuclear watchdog agency.
Diplomatic activity has intensified as the new deadlines approach.
U.S. President Barack Obama has said a further extension would make little sense without a basis for continuing discussions.
Kerry said on February 21 that there was no doubt Obama was serious.
He said Obama "is fully prepared to stop these talks if he feels that they're not being met with the kind of productive decision-making necessary to prove that a program is in fact peaceful."
Zarif said Iranian President Hassan Rohani would not accept a small, short-term agreement, nor a broad accord that left room for interpretation.
Obama is under pressure from critics at home and from Israeli Prime Minister Benjamin Netanyahu, who has warned against any deal that might fail to prevent Iran from developing nuclear weapons.
Netanyahu said on February 22 that the talks could end by allowing Iran "to develop the nuclear capabilities that threaten our existence," and that it was "astonishing" they were continuing.