This is according to a tweet by Fox Business' White House correspondent Edward Lawrence, who cited an unnamed source as saying that Saudi Arabia's King Salman had made the assurance to President Biden during their meeting on July 16.

Higher oil production was one of the reasons for President Biden's visit to the Kingdom last month, although the White House refrained from stating it openly.

Hopes among observers were weak, and indeed the President's visit ended without any major announcements regarding the world's oil supply.

Soon after the visit, however, Crown Prince Mohammed, son of Salman and the de facto ruler of OPEC's biggest producer, talked about spare capacity, saying the maximum Saudi Arabia could do was 13 million bpd.

"The kingdom has announced an increase in its production capacity level to 13 million barrels per day, after which the kingdom will not have any additional capacity to increase production," Mohammed said during the U.S.-Saudi summit where he met with Biden.

Meanwhile, other reports have it that OPEC+ plans to leave September oil production flat compared to August.

A recent Reuters survey showed that OPEC had increased its production by 310,000 bpd in July, is about half of what OPEC+ said it would deliver in July and August to help rebalance oil markets. In June, the OPEC+ Joint Ministerial Committee recommended that the monthly production boost was increased from about 420,000 bpd to 648,000 bpd in the following two months.

OPEC+ is meeting tomorrow in Vienna to discuss crude oil production in the month ahead.