A year and half of nuclear talks between Iran and major powers were creeping towards the finish line on Friday as negotiators wrestled with sticking points including questions about Tehran's past atomic research.
Iran is in talks with the United States and five other powers - Britain, China, France, Germany and Russia - on an agreement to curtail its nuclear program in exchange for relief from economic sanctions.
"We are coming to the end," said a senior Western diplomat, who added there was no plan to carry on for long past next Tuesday. "Either we get an agreement or we don't," he said, adding that the process "remains quite difficult".
Iranian Foreign Minister Mohammad Javad Zarif told Iranian state television that "a lot of progress has been made, but still various technical issues remain that need the other party's political will".