Foreign Minister Mohammad Javad Zarif said Sunday that Iran has been negotiating a 25-year accord with China whose terms will be announced once a deal is struck.
"With confidence and conviction, we are negotiating a 25-year strategic accord with China," Iran's top trading partner, he told a stormy session of parliament.
China is also a key market for Iranian crude exports, which however have been dampened by US sanctions imposed after Washington's 2018 withdrawal from a nuclear deal with Tehran.
An accord with China has been a hot topic on Iranian social media since populist ex-president Mahmud Ahmadinejad last month denounced negotiations underway with a foreign country.
But Zarif, who came under fire over the 2015 nuclear accord which Iranian conservatives had opposed, insisted there was "nothing secret" about the China deal.
The nation would be informed "when an accord has been concluded", he said, adding it had already been made public in January 2016 when Chinese President Xi Jinping visited Tehran.