Iran’s oil minister, Bijan Zanganeh, said on Sunday that the Islamic Republic would only cooperate in restraining output once its own production levels hit 4 million barrels a day, roughly where they were before the impositions of U.N. sanctions over its nuclear program in 2012.

That’s tantamount to a refusal to join any output deal soon, given that the country is only producing around 3.3 million barrels a day currently, and that analysts view its plans to add another 500,000 b/d this year as highly ambitious.

Global benchmark Brent crude futures fell back below $40 a barrel, trading at $39.69 at 0503 EDT, down 70 cents on Friday’s close. Brent hit a 12-year low of $27.10 in January. U.S. crude was down 79 cents at $37.71 a barrel.

“Oil is down because Iran said they would only join the output freeze group once they reached production of 4 million barrels a day (bpd),” said Tamas Varga, oil analyst at London brokerage PVM Oil Associates.

Zanganeh is to meet his Russian counterpart Alexander Novak, another key player in coordinating output restraint between OPEC and non-OPEC countries in Tehran on Monday, according to news agency reports.

Saudi Arabia appeared to have stuck to a preliminary deal with some other producers to freeze output as its crude production held steady in February at 10.22 million bpd, an industry source told Reuters.

Worries about demand fundamentals also moved back into the spotlight as investment bank Morgan Stanley warned that a slowing global economy and high production would prevent any sharp rises in oil prices.

“Oil prices now seem to have bottomed, even though they are likely to stay subdued for the rest of this year before starting to move higher in 2017,” the U.S. bank said in a research note, adding that cheap oil had not provided the boost to growth that many had hoped for.

London-based consultancy Oxford Economics, meanwhile, warned that “without significant changes to supply of the order of several million barrels per day, the market is likely to remain over-supplied for the foreseeable future, which should limit how far oil prices can rally without significant cutbacks in OPEC production.”

“Only when oil demand and supply move back into line do we expect oil prices to stage a gradual recovery,” it said.