Iran's foreign minister says Tehran is unlikely to reach a final nuclear accord with world powers by a November deadline.
Parliament's news website quoted Mohammad Javad Zarif on Friday as saying that even if a general agreement is reached before the deadline, the two sides will require more time to discuss details.
"Hence, it is unlikely to reach a final conclusion before a four-month span," he said.
Zarif said the talks could "quickly" reach a conclusion if world powers show "strong will".
He said the other side has moved cautiously over the past few months but that the negotiations are making progress.
Iran and the P5+1 group - the US, Britain, France, Russia and China plus Germany - in July extended their nuclear talks to November.
Western powers have long suspected Iran is secretly pursuing a nuclear weapons capability alongside its civilian program, charges denied by Tehran, which says its nuclear program is entirely for peaceful purposes like power generation and the manufacture of medical isotopes.
Iranian President Hassan Rouhani, a relative moderate, was elected last year after vowing to engage with Western powers to resolve the decade-old nuclear impasse and get crippling sanctions lifted.
Iran's Supreme Leader Ayatollah Ali Khamenei, who makes the final decision on all major issues, has lent support to the talks but expressed doubt they will lead anywhere.
