Eni UK has confirmed a leak from an oil pipeline in Liverpool Bay.
The company said that a limited "hydrocarbons release" of less than 500 barrels occurred on Monday from its pipeline between the Conwy and Douglas Installations.
The leak was approximately 33 km from the North Wales coast.
A spokesman said: "Details of the incident are still being confirmed. The Conwy to Douglas line was shut immediately and remains off.
"All the relevant authorities have been promptly informed and we are working in full collaboration with them.
"There is no impact to any personnel on the installations.
"An Incident Management Team has been mobilised and is working closely with the relevant authorities and response contractors to understand the situation and minimise any effect to the environment."
The Conwy oil field located in the East Irish Sea, UK has been in production since March 2016.
The well stream from the Conwy platform is transported through a 12km-long, 8in-diameter subsea pipeline to the Eni-operated Douglas platform for processing.