A Romanian master and a UK national employed as a vessel security guard have emerged as those who died in the suspected drone attack on a Zodiac Maritime product tanker off the coast of Oman on Thursday.

Romania’s Ministry of Foreign Affairs (MAE) has condemned the incident targeting the 49,992-dwt Mercer Street (built 2013), which it said killed the ship’s captain, as “completely unacceptable”. The individual was not named.

MAE has asked the Iranian authorities for explanations and summoned Iran’s ambassador for a meeting.

The MAE said in a statement: “Given the aspects presented by Romania’s international partners concerning the fact that the attack was deliberate and coordinated by Iran, Romania asks Iranian authorities to offer explanations right away and reserves the right to act accordingly, alongside its international partners, for an adequate response.”

British maritime security firm Ambrey has said the attack killed one of its employees on board without naming the individual.

The Fiji Sun named the man as Fijian-born former British Army veteran Adrian Underwood.

Those following the incident said the Mercer Street is currently locked down at anchor off Fujairah with nobody allowed to go aboard as different authorities investigate the incident.

They said photos show the main damage was to the tanker’s accommodation block which appears to have taken the main hit with about half of the bridge equipment affected.

The ship’s engine is said to be functioning and its hull intact.

The vessel was escorted to its anchorage by the American nuclear-powered aircraft carrier USS Ronald Reagan and the guided missile destroyer USS Mitscher.

The crew members are expected to be taken off the ship and replaced when investigations allow.