“Solong collided with tanker Stena Immaculate. Both vessels are abandoning. Vessels who have firefighting equipment or who can assist with search and rescue, contact Humber Coastguard on channel 16.”

Broadcast at 10am on a foggy Monday morning, the cold and impartial radio distress call cut straight to the heart about what had just happened off the East Yorkshire coast.

The MV Solong, a 7,850-tonne container ship, had crashed into the anchored tanker Stena Immaculate a few miles from the Humber estuary, which is home to Britain’s busiest commercial port at Immingham.

The Prime Minister’s spokesman said it was an “extremely concerning situation” and a US government source told one maritime blog that foul play could not be ruled out as a cause of the crash.

A ship such as the Stena Immaculate, carrying a volatile and highly flammable cargo, could have been an ideal target for a group trying to disrupt US military operations.

Although a civilian vessel, the ship had been chartered by the US Military Sealift Command as part of a scheme where American-registered tankers previously nominated by their operators are called up for government duty.