Maersk Line, the world's biggest container shipping company, said the search continued on Wednesday for four missing crew members after one of its new-build container vessels caught fire in the Arabian Sea.
It was still unclear how the Maersk Honam container vessel, built in 2017 at the Hyundai Heavy Industries shipyard in South Korea, caught fire, Maersk said.
Another 23 crew members had been safely evacuated from the vessel after the fire broke out at around 1520 GMT on Tuesday, about 900 nautical miles southeast of Salalah, Oman.
The situation is "very critical" as the fire continues and the cause of the fire is not known yet, a spokeswoman for Maersk - a unit of Danish shipping firm A.P. Moller-Maersk A/S - said in an email on Wednesday.
The Maersk ship was en route from Singapore towards Suez. Two of the evacuated crew members received medical aid onboard another container vessel en route to Colombo, Sri Lanka, Maersk said.
"At this stage we have no reason to believe the fire was caused by an error in the ship's construction," the Maersk spokeswoman said in the email.
The 27 crew members comprised 13 from India, nine from the Philippines, two Thai nationals and one each from Romania, South Africa and the United Kingdom.
Maersk did not disclose the identity of the four missing crew members, but said relatives had been informed of the situation.
"What we can say is that this is a very serious fire," the spokeswoman said. "We are continuing the search and rescue operation for the four missing crew members."
Maersk said the crew of Maersk Honam sent out a distress signal after unsuccessful firefighting efforts on Tuesday.