Prof Rodney Forster, director of the Hull Marine Laboratory at the University of Hull, accompanied a BBC crew on a boat to take water samples near the crash site.

Prof Forster said the results were “very good” with “no adverse signs”.

The US-registered tanker Stena Immaculate was carrying 220,000 barrels of aviation fuel during the collision with a Portuguese-flagged cargo ship off the East Yorkshire coast.

Prof Forster told BBC Radio Humberside further testing was needed but the first results were “promising”.

“We have quite a sensitive testing kit that allows us to work out basically how healthy the little cells that live in the water are,” he said.

“It seems that life in the water, at least the small cells, may be unaffected so far.”

He added there had been no reports of dead or sick seabirds being washed ashore which was “a good sign”.

The professor took the samples on Wednesday close to the edge of the safety exclusion zone around the Stena Immaculate.

He described the burnt out wreckage of the tanker as an “amazing sight”.

Salvage crews are assessing the damaged vessel and Prof Forster said moving the vessel was an “enormous engineering challenge”.

“Very, very risky operation,” he said.

“I don’t know whether they would try to move them first or try and get off the kerosene.”

The East Yorkshire coast is home to a wide range of wildlife, especially birds which gather at Spurn Point and cliffs at Bempton and Flamborough.

Prof Forster said the weather conditions at the time of the collision may have helped mitigate any pollution from the tanker, especially with a northerly wind blowing at the time.

“With the high waves and also bright sunny weather, the sun breaks down the hydrocarbons on the sea surface,” he said.

“So a lot of the material has been taken care of by nature.”

The Portuguese-flagged Solong and US-registered tanker Stena Immaculate crashed off the East Yorkshire coast at about 10:00 GMT on Monday.

Filipino national Mark Angelo Pernia, 38, was named as the crew member of the Solong who was missing and presumed dead, the Crown Prosecution Service said.

Vladimir Motin, 59, of Primorsky in St Petersburg, Russia, captain of the Solong, did not enter a plea and was remanded in custody by Hull magistrates to appear before the Central Criminal Court in London on April 14.

Mr Motin stood in the glass-front dock at Hull Magistrates’ Court for the 35-minute hearing.

He spoke through a translator to confirm his name, age and address, and that he understood the charges.

The court heard how all 23 people on the tanker were rescued along with 13 of 14 crew members from the Solong but that Mr Pernia could not be located.

Humberside Police arrested Mr Motin on suspicion of gross negligence manslaughter on Monday evening, hours after the collision.

The force said he had been charged on Friday evening.

The Marine Accident Investigation Branch (MAIB) is trying to establish the cause of the crash.

It said initial inquiries 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.

On Friday, Stena Bulk said salvage experts from SMIT Salvage had successfully boarded Stena Immaculate to conduct a thorough assessment. The vessel was carrying 220,000 barrels of aviation fuel.

The Stena Immaculate is still at anchor at the point where the collision happened, which is about 12 miles off the East Yorkshire coast, near Withernsea.

The MAIB said the salvage process was “necessarily methodical, comprehensive and ongoing” and would “require time to complete fully”.

Chief coastguard Paddy O’Callaghan said that aerial surveillance flights continued to monitor the vessels and confirmed “there continues to be no cause for concern from pollution” from either ship.

All 23 crew on board Stena Immaculate were Americans who are currently in Grimsby and are likely to be repatriated in due course, the BBC understands.

Video posted on Telegram by Russia’s Southern Transport Prosecutor’s Office, appears to show one of the tankers broken in half and sinking amid a heavy storm, with streaks of oil visible in the water.

At least one crew member is believed to have died – and Russian authorities are investigating for criminal negligence, according to TASS news agency.

The incident took place in the Kerch Strait, which separates Russia from occupied Crimea.

A rescue and clean-up operation is under way involving tugboats, helicopters and more than 50 personnel, TASS news agency reported.

“Today, as a result of a storm in the Black Sea, two tankers, Volgoneft-212 and Volgoneft-239, sank,” Russia’s federal sea and inland water transport agency, Rosmorrechflot, wrote in a statement.

“There were crews of 15 and 14 people on board the ships. The accident resulted in a spill of oil products,” it continued.

Both tankers have a loading capacity of about 4,200 tonnes of oil, Reuters news agency reported.

The full extent of the oil spill remains unclear.