Stena Bulk is demanding physical access to its MR2 tanker Stena Impero, held captive in the Strait of Hormuz since 19 July.
The Iranian Revolutionary Guard seized the 49,638-dwt vessel while it was sailing international waters in the strait under the guidance of 23 seamen.
"Following a letter from Iranian authorities to the United Nations Security Council outlining alleged violations of international rules and regulations, including an unconfirmed collision, Stena Bulk and Northern Marine Management consider it imperative we are granted access to the vessel to conduct a full assessment," the company said in a statement today.