A ship off the UAE coast near the Strait of Hormuz has been taken by unknown people and is now headed towards Iranian waters, a UK maritime agency said on Thursday.

The vessel was "taken by unauthorised personnel whilst at anchor" 38 nautical miles or 70 kilometres northeast of Fujairah, and "is now bound for Iranian territorial waters", according to the United Kingdom Maritime Trade Operations (UKMTO) centre.

The UKMTO did not identify the vessel or who was behind its capture and said it was investigating. It also advised ships in the area to report any suspicious activity.

Several ships have been seized or attacked in or near the key waterway as Iran and the US push on with rival blockades.

India's foreign ministry condemned an attack on an Indian-flagged ship off Oman as "unacceptable" on Thursday, with maritime security monitors reporting the cargo vessel had sunk.