Iran's foreign minister, Mohammad Javad Zarif, said Friday that Tehran is unlikely to reach a final nuclear accord with world powers by a November deadline, The Associated Press (AP) reported.
The Iranian parliament's news website quoted Zarif 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 Western powers are trying to turn the interim nuclear deal reached in November into a permanent agreement.
The sides recently committed to a four-month negotiating extension through November 24, after they were unable to reach a permanent deal by a July 20 deadline.
The accord is aimed at easing fears once and for all that the Islamic republic might use its civilian nuclear program to build an atomic bomb, something Tehran has always denied.
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.
On Wednesday Khamenei said the United States had only grown more hostile to Iran since the talks began, and that there was no point in holding direct negotiations with Washington.
Rouhani, meanwhile, has been a subject of criticism by hardliners in his country who are opposed to making a deal with the West.
This week, Rouhani fired back at his critics and suggested that they “go to hell”.