Iran’s oil exports, which have been rising following secret diplomacy with the US, are likely to have peaked for this year as demand in Asia wanes with the end of summer, according to people with knowledge of the country’s sales.    

The Islamic Republic has found new buyers in smaller private refiners in China looking for supply following OPEC+ production cuts, the people said, asking not to be identified because the information is private. But seasonal maintenance at plants is likely to crimp demand, they said.

Iran has been sending more oil into global markets amid easing relations with the US. The two nations have agreed on prisoner exchanges and the unblocking of frozen assets, while the International Atomic Energy Agency reported Monday that Tehran has slowed output of highly-enriched uranium.

The people familiar with Iran’s sales said flows are currently running at about 2 million barrels a day, close to the country’s capacity. While Tehran can boost exports again when demand returns, they’re unlikely to be higher than the current levels. The volume compares with the 1.85 million a day that TankerTrackers.com Inc. said was shipped in August. Estimates can vary as ships sometimes turn of transponders.

US officials have privately acknowledged a gradual relaxation of some sanctions enforcement on Iranian oil sales. Those additional volumes are almost all going to China, whose imports are at a decade high. But the Middle Eastern nation is also competing with Russia for buyers there as the flow of Moscow’s discounted barrels remains high despite the price exceeding the Group of Seven’s cap of $60 a barrel.

Crude shipments from Iran to China have jumped to between 1.4 million barrels a day and nearly 1.9 million a day, according to tanker tracking and analysts, from levels below 1 million a day last year.

Beyond the seasonal demand impact, the already high exports and production will limit how much more the nation can ship in the longer term, said Russell Hardy, chief executive officer of trader Vitol Group. Output has already reached 3.1 million barrels a day, he said at the APPEC conference by S&P Global Commodity Insights in Singapore on Monday. Iran expects to boost that to 3.4 million a day, close to the pre-sanctions capacity of 3.8 million barrels.