U.S. Secretary of State John Kerry has said there is a limited time for talks between Iran and major powers about its disputed nuclear programme.
"There is a finite amount of time," Kerry, on a visit to Saudi Arabia, said of the talks between Tehran and a group of world powers. He was speaking at a news conference held jointly with his Saudi counterpart Prince Saud al-Faisal.
Iran was upbeat last week after talks in the Kazakh city of Almaty with world powers about its nuclear work ended with an agreement to meet again, but Western officials said it had yet to take concrete steps to ease their fears about its atomic ambitions.
The United States, China, France, Russia, Britain and Germany offered modest sanctions relief in return for Iran curbing its most sensitive nuclear work but made clear that they expected no immediate breakthrough.
Prince Saud suggested that the Iranians did not show enough seriousness in the Almaty talks.
"We can't be like philosophers who keep talking. We have to talk seriously and honestly and we have to put in our commitment clearly on the table," he said.
"Negotiations cannot go on forever," he added.