Saudi Arabia and Russia won't add significantly more oil to the market because of a lack of capacity, a top Iranian official said yesterday, predicting prices will probably rise further.

On Sunday, ministers and officials from the Organization of the Petroleum Exporting Countries (OPEC) plus Russia and other allies ruled out an immediate oil-output boost, in effect rebuffing U.S. President Donald Trump's calls for action. The move helped push crude prices to a four-year high near $81 a barrel.

Also underpinning the market is the prospect of lower exports from Iran, OPEC's third-largest producer, due to U.S. sanctions. Iran's OPEC governor, Hossein Kazempour Ardebili, said in comments to Reuters that Saudi Arabia and Russia were unable and unwilling to add more production at short notice. "They are doing little and late, to get prices higher," he said. "They got prices higher and they are going to get them higher still."