The biggest buyers of Iranian oil are reportedly putting their purchases on hold as they wait to see whether the White House will extend waivers allowing them to keep buying the crude.

Most Asian buyers are avoiding imports for next month as it's unclear what will happen to the exemptions that are set to expire in the first week of May, according to sources with knowledge of that matter. Even if the waivers are extended, it would be too late to order and receive cargoes for the month, they said.

Washington's surprise decision last year to allow eight nations to keep buying Iranian oil was a big contributor to the plunge in crude prices in the fourth quarter. While the White House appears keen to keep the pressure on the Persian Gulf nation, analysts have speculated that preventing further gains in oil prices is a bigger priority for U.S. President Donald Trump.