Missing Titanic sub search team expand search area as oxygen fears mount

More noises have been detected in the search for a submersible which went missing on Sunday while on a dive to see the Titanic wreck site, the US Coast Guard says.

Capt Jamie Frederick said they did not know what the noises were and the US navy was helping analyse them.

Meanwhile rescuers have expanded the search area to twice the size of the US state of Connecticut, he said.

More boats and underwater vehicles were due to join the search on Thursday.

Speaking during a press conference in Boston Capt Frederick said a Canadian search plane had picked up underwater noises on Tuesday and again on Wednesday.

That had prompted the search team to switch its focus to the area the noises were detected.

But it remained unclear what the noises were and underwater searches of the area they were detected in had not yet yielded anything.

With the arrival of more boats and underwater vehicles, search operations would also resume where the search was originally taking place, he said. The overall area of sea being scoured was about 26,000 sq km (10,000 sq miles).

"You always have hope," Capt Frederick said, adding: "This is a search and rescue operation 100%."

There were currently five surface vessels involved in the search, he said, with a further five heading to the area in about a day's time.

Meanwhile the two remotely-operated vehicles (ROVs) searching underwater would be joined by several more on Thursday morning.

"We're searching where the noises were detected. In the morning we'll continue to search there and put additional ROVs down where the search was originally taking place," he said.

Earlier on Wednesday Rear Admiral John Mauger from the US Coast Guard told the BBC that the submersible could have less than 20 hours of oxygen left, based on the initial estimate of 96 hours.

"One of the factors that makes it hard to predict how much oxygen is left is that we do not know the rate of the consumption of oxygen per occupant on the sub," he said.

On board the 21-foot vessel is British businessman Hamish Harding, British-Pakistani businessman Shahzada Dawood and his son Suleman, former French navy diver Paul-Henry Nargeolet and the CEO of OceanGate - which operates the submersible - Stockton Rush.

However Oisin Fanning, who has been on a deep sea voyage to the Titanic wreck before and knows some of those on board the missing submersible, told the BBC the crew would understand how to maximise their oxygen supply.

Mr Fanning said those on board will have gone through rigorous training beforehand and "will immediately look to conserve oxygen straight away."

"They will do everything to keep themselves calm, breathe shallowly and preserve the oxygen for as long as possible," he said.