Saudi Arabia and neighbouring Kuwait jointly claim the offshore Al-Durra gas field. Iran says it has rights to the field, which it refers to as Arash. The two sides held talks in Iran in March but were unable to agree on a border demarcation.

Nasser Kanaani, a spokesman for Iran's Foreign Ministry, said on Monday that it would not tolerate any infringement on its rights, echoing remarks by the country's oil minister the previous day. Last week, Kuwait's oil minister told Sky News Arabia that his country would commence drilling and production without waiting for a deal.

Saudi Arabia has sided with Kuwait, saying the two countries have exclusive ownership of the field, and has called on Iran to return to negotiations.

Saudi Arabia and Iran, which have backed opposite sides in conflicts across the Middle East and accused each other of destabilising the region, agreed in March to restore diplomatic relations following a seven-year freeze. They have since reopened embassies and welcomed senior officials on visits.

But they continue to back opposite sides in Yemen's civil war, which is ongoing despite a 15-month cease-fire. Saudi Arabia is also in negotiations with the United States over potentially normalising relations with Israel, which Iran's leaders have said should be wiped off the map.

It's unclear whether the dispute over the gas field, which goes back to the 1960s, will escalate beyond rhetoric. But tensions are already high in the Persian Gulf, where the US is building up military forces in response to what it says is Iran's unlawful seizure of oil tankers and harassment of commercial vessels.

Saudi Arabia and Kuwait agreed last year to jointly develop the gas field. Kuwait said at the time that they aimed to produce 1 billion cubic feet of natural gas and 84,000 barrels of liquefied gas per day. Iran denounced the agreement as illegal and said it should be included in any such plans.