Abu Dhabi National Oil Company (Adnoc) is trimming crude volumes slated for Asian buyers in August and September, according to sources familiar with the matter, a move that has already lifted the premium of its flagship Murban crude grade to near its highest level since April against the global Brent benchmark.

Murban, the UAE's primary crude grade and a key gauge of market conditions for Asian purchasers, has seen its premium over Brent climb to levels not witnessed since April this week, at one point nearing $7 per barrel. This marks a sharp reversal from early August, when the grade was still trading at a discount to the benchmark.

The supply reduction will amount to roughly 5% of cargoes sold through the spot market, the sources indicated. They added that the cut applies exclusively to volumes purchased via over-the-counter (OTC) transactions, meaning physical crude bought through the ICE Futures Abu Dhabi exchange remains unaffected.

This 5% supply trim falls within the so-called "operational tolerance" band, a flexibility mechanism that permits fluctuations in supply volumes to accommodate unexpected technical constraints. Traders noted that Adnoc has not provided a specific rationale for the reduction, though another individual with knowledge of the situation attributed it to planned maintenance at Abu Dhabi's onshore oil fields.

Notably, in March, shortly after the outbreak of Middle East hostilities, Adnoc had announced in a regular online export schedule that it would postpone maintenance work originally slated for May through September, citing the "current situation in the Gulf region."

Amid ongoing geopolitical tensions in the Middle East, Adnoc has been among the most successful producers at moving crude out of the Persian Gulf. The company employs a so-called short-haul transshipment strategy, where vessels typically switch off their transponders to avoid detection, make short voyages, and then transfer cargoes to other ships outside the Gulf.

It remains unclear whether the reduction in crude volumes to Asian customers for August and September stems from the field maintenance cited by sources or from heightened regional tensions. The memorandum of understanding between the US and Iran, aimed at moving the two nations toward a permanent agreement, expired on Monday. With the pact's expiration, both sides have signaled hardline stances, ruling out any extension of the temporary arrangement.

On August 17, US President Donald Trump stated that Iran would not reach the agreement he deems necessary to end the US-Iran conflict, asserting that the country "should surrender." Iranian Foreign Minister Abbas Araghchi responded that "there is no 60-day ceasefire period that needs to be extended." In related developments, a US official reported that Trump has instructed senior government envoys to suspend engagement with Iran.