US Secretary of State Marco Rubio on Thursday warned of “total chaos” if ships were charged to pass through the vital Strait of Hormuz, as Oman said it too rejected imposing fees.

The comments from Rubio and his Omani counterpart came after the top US diplomat met with Gulf foreign ministers at the end of a three-day regional tour.

Iran and Oman, which straddle the narrow waterway, had earlier said they were considering charging costs related to the strait, insisting they held sovereignty over it.

The Hormuz normally carries one-fifth of the world’s crude oil and liquefied natural gas, but it was all but closed by Iran during the Middle East war, sending energy prices soaring.

“International waterways do not belong to any nation state. This is a foundational principle in the world today, without which the world would be in total chaos,” Rubio told a Gulf Cooperation Council meeting in Bahrain.

“If in fact we accepted that you can charge money to use an international waterway because it happens to be near your territorial space, well then this will spread throughout the world like a contagion.”

Iran lifted its blockade of the Hormuz after it struck an initial deal with the US to end the Middle East war, and negotiations on a permanent settlement of the conflict are ongoing.

Before Rubio’s remarks, Iran reiterated that ships must seek its authorisation before crossing.

But Oman also announced a new temporary route through the strait running close to its coast, which Iran appeared to denounce.

Omani Foreign Minister Badr Albusaidi told Thursday’s meeting that “future arrangements regarding the Strait do not entail the imposition of any transit fees”, his ministry said.

‘Zero support’

Rubio said there was “zero support” for Hormuz tolls among Gulf countries, which rely heavily on the strait to export their oil and gas.

He added that relations with Oman — which US President Donald Trump threatened to “blow up” last month over alleged attempts to control Hormuz — were now “fine”.

“I mean, ultimately there’s not going to be any fees or tolls. They (Oman) were there in the meeting today and they said that they are not in favour of the tolling system,” Rubio said.

The future of the strait, only about 30 kilometres (18 miles) wide at its narrowest point, is a key sticking point in the negotiations between Tehran and Washington.

After Oman announced its temporary route through the strait, Iran’s Revolutionary Guards denounced the move by “certain authorities”, without naming them.

The Guards, the ideological arm of Iran’s military, also said “the only authorised route… is the route announced by the Islamic Republic of Iran”.

Oman said the new corridor was coordinated with the International Maritime Organisation, the UN agency responsible for marine safety.

The memorandum of understanding signed last week by Tehran and Washington to end their war stipulated that commercial ships may transit the strait free of charge for the next 60 days.

It is unclear what arrangements will be in place after that period.

Rubio said the US wants a lasting settlement with Iran to permanently end their war, but not “at any price”.