Attempts are underway to remove more than 40,000 litres of fuel from a stricken cargo ship which ran aground in rough seas, sparking the rescue of seven crew members.
The ship has leaked a "small quantity" of oil into surrounding waters, the Environment Agency said. However overall the environmental impact is said to be "minimal" despite the dramatic pictures.
The main fuel supply for the boat, which hit rocks near Colwyn Bay in North Wales on Tuesday night, is still thought to be intact, the Marine and Coastguard Agency (MCA) said.
Oil which was in use at the time has seeped out of the 82-metre long vessel but the impact of the oil leak is expected to be "minimal", Environment Agency Wales said.
A spokeswoman said: "A small quantity of gas oil has already leaked from the vessel, and officers are advising the MCA on how best to remove the remainder of the fuel without damaging the environment.
"If more fuel were to leak from the vessel, current predictions are that it would be confined to a small area between Colwyn Bay and Rhyl.
"As much of the escaping gas oil is likely to evaporate and be dispersed by the sea, its environmental impact is expected to be minimal at this stage.
"Officers have also been patrolling the beaches on either side of the incident checking for signs of pollution. So far, no traces of pollution on the beaches have been found."
An MCA spokeswoman added that the ship sustained damage to its starboard side.
She said: "The 'Carrier' has been holed in three places on the starboard side. It's reported that the port side, where the fuel tank is located, is intact."
On Tuesday two lifeboats and Royal Navy and RAF helicopters were involved in the dramatic rescue of the seven Polish crew members after the vessel got into difficulties as the Welsh coast was battered by Gale Force Nine winds and five metre swells.
Five of the seamen were rescued by a Royal Navy Sea King rescue helicopter scrambled from RNAS Prestwick.
But the aircraft developed a problem with its winch wire, forcing rescue co-ordinators to send out a second helicopter from RAF Leconfield in Yorkshire to collect the remaining two crew members.
The seamen were taken by ambulance to North Wales Police headquarters in Colwyn Bay where they were given hot drinks and a change of clothes and transported to a nearby hotel, said North Wales Police.
Assistant Chief Constable Gareth Pritchard added: "This was a very difficult operation involving many agencies in very bad weather. Everyone is delighted that the seven crewmen were rescued without injury and they are safe and well."
During the five-hour long operation the A55 was closed to allow emergency workers safe access to the vessel.
The ship, which is registered in Antigua and Barbuda and was carrying a cargo of stones, is now resting against concrete blocks on the beach at Llanddulas, which runs adjacent to the road.
Members of the coastguard, North Wales Fire and Rescue Service, ambulance and police service remained at the scene overnight along with North Wales Trunk Road Agency officers.
First Minister of Wales Carwyn Jones praised emergency services' "heroic efforts".
He said: "I would like to send my deepest appreciation and thanks to all those who took part in last night's operation.
"The weather and sea conditions they faced were atrocious.
"The dedication and professionalism of our emergency services is something we can all be exceptionally proud of.
"The Welsh Government was kept fully informed of developments throughout the night.
"Our focus now will be to offer any assistance necessary to salvage the ship and to ensure every effort is made to lessen any potential environmental impact."
The MCA said the reason for the ship running aground was not yet clear.
An MCA spokeswoman said that there had been a small amount of oil lost, which was being dissipated, partly assisted by continuing poor weather.
"At the moment, the salvors are drawing up plans to deal with removal of the oil, then the cargo of stone, and the vessel."