Video said to show Iranian troops boarding MSC Aries in the Strait of Hormuz.
Iran has been accused of seizing a commercial ship with links to Israel as it passed through the Strait of Hormuz.
A video filmed from inside MSC Aries and obtained by Reuters news agency appears to show two people rappelling onto the vessel from a helicopter.
Iranian special forces boarded the ship about 50 miles (80km) off the coast of the United Arab Emirates, a statement from the ship's operator MSC said.
The country's state news agency, Irna, said the naval branch of the Islamic Revolutionary Guards Corps (IRGC) had seized the MSC Aries as it was "linked to Israel".
