British navy and French gendarmerie vessels are patrolling waters around Jersey amid fears of a possible blockade by about 60 French fishing boats which gathered off the island "like an invasion".
A flotilla of French boats headed towards the Channel island's port of St Helier at about 5am, with angry fishermen lighting flares and waving banners calling for fishing access to the waters.
A freight ship was initially "trapped" and unable to leave the harbour, but was later allowed to pass as the row over post-Brexit fishing rights between the UK and France escalated on Thursday.
Two local boats were said to have joined the demonstration as police and islanders looked on.
The Royal Navy's HMS Severn and HMS Tamar, armed with machine guns and cannon, were positioned miles away after being sent to the island's main port to “monitor the situation” following mounting threats from Normandy trawlermen.
A French gendarmerie vessel armed with cannon patrolled waters several miles from the flotilla as the situation in St Helier unfolded and a French fishing industry official warned "we're ready for war".