Maersk said on Wednesday it had learned from the ship's management that the 24-member crew was safe and in good spirits "under the circumstances" in Iran's port of Bandar Abbas.

Iranian patrol boats intercepted the ship, the 65,000-ton Maersk Tigris, early on Tuesday in international waters, according to the Danish charterer, adding that the reason was unknown.

"We are continuing our efforts to obtain more information about the Iranian authorities' seizure - in international waters," said Maersk.

Denmark's Foreign Ministry said it was also seeking more information.

Debt complaint?

Iranian state media said the seizure stemmed from a complaint about debts lodged by a private Iranian company.

The Maersk Tigris, is flagged by the Marshall Islands in the Pacific and crewed by Rickmers Shipmanagement, a firm based in Hamburg, Germany.

Rickmers said its staff on board were mostly from eastern Europe and Asia.

Tuesday's seizure in the Hormuz waterway, an export route for a fifth of the world's oil, prompted the US to send a destroyer and maritime patrol aircraft which routinely patrol the area.

The Maersk Tigris' captain had initially refused an Iranian order to move into Iranian waters, according to a Pentagon spokesman, but complied after warning shots from Iranian patrol boats.

Bandar Abbas is Iran's main commercial port and is also used by Iranian naval forces.

Coincidence?

The standoff coincides with a critical moment in US-Iranian relations, given a tentative nuclear deal reached in Geneva last month.

It also coincides with heightened tensions between Iran and Saudi Arabia over the civil war in Yemen, where they suppose opposing sides.

ipj/sms (dpa, Reuters, AP)