The top U.S. and Iranian diplomats are meeting in Vienna in a last-ditch effort to reach a comprehensive deal on Tehran's nuclear program, but an accord appears unlikely before Monday's deadline.
U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif started a fifth round of talks Sunday, with Russian Foreign Minister Sergei Lavrov set to join them later Sunday.
The Iranian Students News Agency quoted an unidentified member of Iran's negotiating team as saying a new pact will not be possible with the short time left until the deadline and the number of issues yet to be resolved. Iran said it would start discussion of an extension to the talks if no agreement is reached by Sunday night.
Kerry said Saturday "serious gaps" remain in the talks. He recently said the United States and its P5 Plus 1 allies - Britain, China, France, Germany and Russia - are not considering an extension past Monday's target date.
German Foreign Minister Frank-Walter Steinmeier said the main question is if Iran is ready to end its research on acquiring a nuclear weapon.
Israeli Prime Minister Benjamin Netanyahu voiced new fears Sunday that the countries negotiating with Iran will leave it with the ability to create a nuclear weapon.