Presumed human remains have been found within the wreckage of the Titan submersible, the US Coast Guard told the media.

Pieces from the sub, which imploded on a deep dive to the Titanic, were unloaded in St John's, Canada, on Wednesday.

Officials say the sub's landing frame and a rear cover were found among the debris.

US medical professionals will conduct a formal analysis of presumed remains, the coast guard said in a statement.

The agency is in the early stages of an investigation into the causes of the disaster. The Coast Guard's Marine Board of Investigation (MBI) will transport the evidence to a US port for further analysis and testing.

MBI chair Capt Jason Neubauer said in a statement that there was "still a substantial amount of work to be done to understand the factors that led to the catastrophic loss of the Titan and help ensure a similar tragedy does not occur again".

"I am grateful for the coordinated international and interagency support to recover and preserve this vital evidence at extreme offshore distances and depths," Capt Neubauer said.

All five people on board the vessel died on 18 June after it imploded about 90 minutes into a dive to view the famous 1912 shipwreck, which sits at a depth of 3,800m (12,500ft) in the north Atlantic.

The passengers were the head of OceanGate, which organised the dive, 61-year-old Stockton Rush; British explorer Hamish Harding, 58; Shahzada Dawood, 48, and his son, Suleman Dawood, 19; and French diver Paul-Henry Nargeolet, 77.