Regular banging noises have been picked up on sonar as rescuers attempt to search for a submersible that went missing on Sunday (June 18).

The vessel, operated by OceanGate Expeditions, was diving to see the wreck of the Titanic, which is around 400 miles off the coast of Newfoundland.

French submersible pilot, Paul-Henry Nargeolet, British billionaire Hamish Harding and chief executive and founder of OceanGate Expeditions, Stockton Rush, were understood to have been on board.

Additionally, the British-Pakistani businessman Shahzada Dawood and his son, Suleman, were on the vessel.

An internal government memo from the Department of Homeland Security (DHS) said banging sounds had been detected every 30 minutes on Tuesday (June 20), Sky News reported.

Four hours later, after additional sonar devices were deployed, banging was still heard, the memo said. 

What action is being taken to find the Titanic tourist submarine?

The US Coastguard confirmed that remote underwater vehicles were redeployed in response to reports of banging to explore the origin of the noises.

It said the searches have yielded negative results but continue.

Data from a Canadian aircraft involved in the search, which detected "underwater noises", has been shared with experts at the US Navy for further analysis, the Coast Guard added.

Around 10,000 square miles had been searched as of Tuesday, but there has been no luck so far in finding the Titanic tourist submarine.

Alongside the existing rescue efforts The Explorers Club says a UK-based deepwater specialist team "can provide invaluable assistance" to the Titan search and it is working on approval for its deployment.

In a letter to members, the club's president Richard Garriott de Cayeux said Magellan's remotely operated vehicles (ROVs) have "been at the Titanic site many times".

Mr Garriott de Cayeux said there is "cause for hope" based on data which shows "likely signs of life have been detected at the site".