WASHINGTON, May 1. /TASS/. US President Donald Trump has called for an immediate halt to all purchases of Iranian oil and petrochemical products, warning that violators will face secondary sanctions.

"All purchases of Iranian oil, or petrochemical products, must stop, now! Any Country or person who buys any amount of oil or petrochemicals from Iran will be subject to, immediately, secondary sanctions," he wrote on his Truth Social platform.

Trump added, "They will not be allowed to do business with the United States of America in any way, shape, or form."

Washington and Tehran have already held three rounds of dialogue with Oman acting as mediator. The Iranian delegation to the talks is headed by Abbas Araghchi, while the US delegation is headed by special presidential envoy Steven Witkoff.