Iran said it is close to concluding a deal with the United States to lift sanctions against its industrial sectors, but at the same time warned that there is little time left for world powers to renew the 2015 nuclear deal.

Iran Foreign Ministry spokesman Saeed Khatibzadeh did not elaborate on the details, but remarked that as long as there are unresolved issues, the signing of the historic agreement will continue to be delayed.

As such, oil markets are monitoring the negotiations, looking closely at clues that OPEC can finally resume its output and sales.

And on Monday, oil prices rose because expectations for an increase in Iranian crude exports weakened.

Khatibzadeh disclosed that there are still some practical, political, legal and technical issues, but assured that negotiations are not deadlocked.

Brent jumped on this news, thereby bringing its gain this year to 42%.

World powers are trying to revive the 2015 nuclear agreement, which the United States abandoned three years ago.

But Iran deputy foreign minister Abbas Araghchi said there is little chance that an agreement will be signed before the presidential elections, which will take place on Friday.

President Hassan Rouhani, who signed the original treaty in 2015, is due to step down in August after serving two terms. Many expect him to be replaced by Ebrahim Raisi, a clergyman widely believed to be hostile to US engagement.

However, a government spokesman said last week that the decision to try to revive the agreement was made by Supreme Leader Ali Khamenei, so Rouhani's departure will not prevent it.