Poole Harbour Commissioners (PHC) reported a leak at a Perenco pipeline under Owers Bay on Sunday.
The public is being advised not to swim in Poole Harbour or the surrounding area until further notice.
Perenco stated that a “full investigation” into what occurred would be conducted.
Poole is Europe’s largest natural harbour and a Site of Special Scientific Interest (SSI) for a variety of wading birds.
PHC stated in a statement: “It is estimated that 200 barrels of reservoir fluid have been released into Poole Harbour’s water column.
“Anyone who has come into contact with the spill should immediately wash their hands with soap and water. If the spill has made contact with the eyes, they should be rinsed with water.”
‘Extremely serious situation’
It went on to say that it had activated its oil spill response plan and that the pipeline had been shut down, with booms placed on either side of the leak.
According to PHC, oil spill response companies have also been mobilised.
According to Perenco, an incident management team was immediately activated to stop the leak, and a clean-up operation was underway.
Franck Dy, general manager of Perenco UK’s Wytch Farm, stated: “Any spill is extremely serious, and an extensive investigation will be launched to determine what occurred in Poole Harbour.
“It is critical to emphasise that the situation is under control, with fluid discharge stopped and the spill contained.”
The Wytch Farm oil field is one of Europe’s largest onshore oil fields, according to the Bournemouth, Christchurch and Poole (BCP) Council, which stated that it was “working as part of a multi-agency response to the major incident declared this afternoon.
Council leader Philip Broadhead said in a statement that the leak had been declared a major incident and that “all relevant partner agencies [were] working together.”
The Environment Agency (EA) reported a “large amount of oil” in Poole Harbour on Sunday afternoon.
The EA stated in a statement, “We are assisting the port authority and other partners in responding to this incident.”
PHC notified Dorset Police of an oil leak in Poole Harbour at 1.43pm on Sunday, according to Dorset Police.
The force stated in a statement that the incident was being led by PHC and that police were not required to attend.
“We will continue to communicate with our partner agencies and offer assistance as needed,” the force added.