The captain of a cargo ship arrested after a collision in the North Sea is being held in custody for a further 24 hours “due to the complexities of the incident”, police said.
The 59-year-old Russian man was arrested on suspicion of gross negligence manslaughter.
The US-registered tanker Stena Immaculate, which was carrying 220,000 barrels of aviation fuel, and the Portuguese-flagged cargo ship Solong crashed off the East Yorkshire coast on Monday.
Humberside Police said detectives were given more time to question the man after magistrates had previously granted a 36-hour extension on Wednesday.
Both ships were engulfed in flames and 36 crew members were rescued.
A crew member of the Solong is missing and presumed dead.
In a statement, Humberside Police said: “Additional time has been imperative to the investigation due to the complexities of the incident with the vessels in the sea, the number of witnesses involved and establishing any scenes to collate and gather information and evidence.
“Extensive lines of enquiry are continuing, and further updates will be provided when we can.”
It said officers were continuing to support the family of the missing crew member, who was “believed to be deceased”.
The force is conducting its inquiry in parallel with the Marine Accident Investigation Branch (MAIB), which is trying to establish the cause of the crash.
On Friday, chief coastguard Paddy O’Callaghan said “only small periodic pockets of fire” on the Solong remained, which were “not causing undue concern”.
He added regular aerial surveillance flights continued to monitor the vessels and confirmed “there continues to be no cause for concern from pollution” from either ship.
The MAIB said its initial enquiries found the Solong was travelling from Grangemouth to Rotterdam and had often sailed the same route.
“At 09:47 GMT it struck the Stena Immaculate that was at anchor off the entrance to the River Humber,” the MAIB said.
The ship was travelling at about 16.4 knots (18.9 mph).
The agency added it was gathering witness accounts and would also look at the “navigational practices on board both vessels; the manning and fatigue management; the condition and maintenance of the vessels involved; and the environmental conditions at the time.”
All 23 crew on board the Stenna Immaculate are Americans who are currently in Grimsby and are likely to be repatriated in due course, the BBC understands.
The MAIB said it was leading the safety investigation into the incident, with Portugal and the US acting as “substantially interested states”.
