A team from deepwater specialists of UK company Magellan Limited, who was supposed to join the rescue mission, has reportedly been waiting for the approval to leave an airport in the Channel Islands since Monday evening.
Bretton Hunchak, former president of RMS Titanic, Inc, which collaborated with Magellan, said that the US government has allegedly yet to authorize the team's request to join rescuers 435 miles south of the Canadian city of St. John's, Newfoundland, the report said.
Magellan can reportedly get down to 5,000 meters (16404,2 feet). Hunchak said that US officials would prefer to use a New York-based vessel capable of operating at depth of 3,000 meters.
UK Prime Minister Rishi Sunak expressed support to the families involved in the accident.
"The families involved will be deeply concerned and his thoughts are with them and the Foreign Office is providing support," Sunak's spokesman was quoted as saying by media.
On Sunday, the submarine of the OceanGate Expeditions company went missing during an expedition to the Titanic wreckage in an area about 900 miles east of Cape Cod in the North Atlantic, at a depth of approximately 13,000 feet. The submarine has a capacity for five people and oxygen supply that can last for 96 hours. Hamish Harding, a billionaire and adventure traveler, is reportedly on board. Since Monday morning, the search and rescue operation is underway.