Tehran has lodged a complaint with the International Maritime Organization (IMO) against the US over the re-imposition of sweeping sanctions, which target scores of Iranian ships as part of Washington's push to cut off the country's oil exports.
In a tweet on Thursday, Iran's Ambassador to the UK said he had submitted a letter to the London-based IMO to voice Tehran's protest at the return of the US sanctions, which it considers to be unlawful.
In the letter, Tehran's Embassy condemns "the imposition by the US of unilateral sanctions on Iran's ships as a measure that violates international maritime law and endangers maritime security."
It also called on the IMO to conduct a "special review" of the matter at its Assembly -- the organization's highest governing body.
As a specialized agency of the United Nations, the IMO – which has 174 member states – is tasked with regulating international shipping.
The complaint was filed days after Washington put back in place a new round of unilateral sanctions against Iran's banking and energy sectors with the aim of cutting off its oil sales and crucial exports.
The US Treasury Department's sanctions list includes over 200 people and ships among more than 700 Iranian or Iran-linked targets.
Washington has not even spared Iran's ill-fated Sanchi oil tanker, which collided with a frigate off China's east coast in January and sank with 32 people on board.
Washington vowed to bring imports of Iranian oil down to zero, but later granted exemptions to eight of Tehran's major customers – including China, India, Japan and South Korea.