Titanic sub: rescuers intensify search as fears grow over Titan’s remaining oxygen supply

Equipment including deep sea vehicles heading to site as theoretical limit of oxygen supply inside Titan submersible nears

• Titan sub search - latest updates

The search for a submersible that went missing during a dive to the wreck of Titanic has entered its fourth day, amid concerns the oxygen supply sustaining its five passengers is running dangerously low.

Equipment from the US, Canada, UK and France is heading to the scene of the search, about 400 miles (640km) south of St John's, Newfoundland, joining an international coalition of rescue teams that is sweeping a vast expanse of the north Atlantic for the Titan after it went missing on Sunday, nearly two hours into its dive.