Denmark's Maersk Line shipping company has urged Iran to release the Maersk Tigris cargo ship and its crew.
Iranian authorities seized the ship on April 28 in the Strait of Hormuz, one of the world's busiest shipping lanes.
The Marshall Island-flagged ship was carrying cargo for Maersk Line and technically was being operated by a German firm, Rickmers Ship Management.
Maersk said it thinks the seizure was related to a long-running legal dispute over uncollected cargo from Dubai.
Iranian Foreign Minister Mohammad Javad Zarif said on April 29 that an Iranian court ordered Maersk Line to pay damages more than 15 years ago.
Iran's ambassador to Denmark on April 30 said the Maersk Tigris cargo ship would be released by Iranian authorities once Maersk Line pays off its debts in the dispute.
The standoff comes as a Saudi-led coalition of Gulf Arab states continues air strikes against Iranian-backed Huthi rebels in Yemen and a U.S. aircraft carrier patrols off Yemen's coast.