A Maltese-flagged cargo ship carrying thousands of tonnes of potentially explosive fertiliser is set to travel through UK waters.
Ruby, which was earlier accompanied by an escort tug, has reportedly been rejected by several countries due to its cargo.
The ship, which has 20,000 tonnes of ammonium nitrate on board, was previously damaged but deemed seaworthy by authorities in Norway.
HM Coastguard is in contact with the vessel, which according to ship tracking data, was in the North Sea off the Kent coast on Thursday morning.
The ship, owned by Maltese firm Ruby Enterprise, set off from the northern Russian port of Kandalaksha in July.
The national maritime emergency service said it will monitor the ship’s progress as it heads towards and through UK waters.
An escorting tug, Amber II, which had sailed with the boat from Norway, left the Ruby on Thursday morning and sailed east. Its current destination is listed as Rotterdam, in the Netherlands.
Though there is no suggestion of immediate danger from the cargo, the same chemical caused a devastating blast at a Beirut warehouse in 2020.
Ammonium nitrate is regularly transported around the world and used as fertiliser but is also used in explosives.
The ship is carrying seven times the amount of ammonium nitrate that caused the Beirut explosion.
Soon after departing Russia, the Ruby briefly ran aground after reportedly encountering a storm.
It then continued its journey around the Kola Peninsula and docked in Tromsø, Norway.
Norway’s Maritime Authority told the BBC the vessel was inspected by DNV Group to ensure it met safety and environmental standards.
The group found damage to its hull, propeller and rudder, but the Ruby was still deemed “seaworthy”.
As a precaution, DNV Group, and the Maltese flag registry, insisted that a tug escort the vessel for the remainder of its journey.
The ship was bound for Klaipeda, in Lithuania, according to ship tracking firm MarineTraffic.
But despite being deemed seaworthy, the ship was denied entry to Klaipeda. Algia Latakas, the port authority’s chief executive, told the BBC that this was “because of its cargo”.
Andrea Sella, professor of chemistry at University College London, said the cargo was not high risk, unless there was a fire on board.
“While I understand the caution of the authorities in Tromsø, I suspect that the chances of a similar disaster to Beirut are relatively modest,” she said.
She added: “It would also be interesting to know what the nature of the repairs might be as clearly welding might significantly raise the potential fire risk.”
Other reports suggested Sweden had imposed a ban as well, but Sweden’s transport agency denies this.
“What the Swedish authorities did was to follow the matter in case we would have needed to act in some way,” a spokesperson told the BBC.
In recent weeks, the Ruby travelled south along Norway’s coast and through the North Sea.
The ship reportedly has had restricted manoeuvrability, though the BBC has been unable to confirm this.
On 25 September, it anchored about 15 miles (25km) north east of Margate, in Kent, near the Dover Strait – one of the world’s busiest waterways.
Its current destination is listed as Marsaxlokk, in Malta.
But Maltese authorities have told local media that the ship can only enter the country if it empties its cargo beforehand.
Marco Forgione, director general of the Chartered Institute of Export & International Trade, raised concerns about potential “environmental damage”.
“Should the ammonium nitrate start to leak out of the ship and contaminate the sea… shipping through the channel would have to be diverted to avoid further shifting the pollution through its waters,” he said.
He added that damage as a result of the potential scenario would be “immense” and cause “ongoing disruption”.