Iran's Islamic Revolutionary Guard Corps (IRGC) has confirmed it seized a tanker on Friday morning in the Strait of Hormuz.
The Talara tanker, sailing under the flag of the Marshall Islands, was travelling from the United Arab Emirates (UAE) to Singapore.
The IRGC said it was found to be "in violation of the law by carrying unauthorised cargo", but did not provide details of the violation. Reports suggest it was carrying high-sulphur gasoil.
Iran has periodically seized tankers and cargo ships travelling in and around the Persian Gulf, which is a key global shipping route for oil and liquefied natural gas.
It has often cited maritime violations such as smuggling or legal issues.
