Boris Johnson has sent two Royal Navy vessels to patrol Jersey waters as the post-brexit fishing row escalates.

The two vessels were sent to Jersey waters amid concerns of a possible blockade of the island.

HMS Severn and HMS Tamar have been deployed by the UK Government to “monitor the situation” at the Channel Island amid a protest by French fishing vessels at the port of St Helier over the lack of access.

Annick Girardin, France’s maritime minister warned that the country is ready to take “retaliatory measures” earlier this week accusing Jersey of dragging its feet over issuing new licences to French boats.

Prime Minister Boris Johnson spoke to Jersey Chief Minister Senator John Le Fondre and External Affairs Minister Ian Gorst on Wednesday, and “underlined his unwavering support” for the island.

Dozens of French boats arrived at the harbour on Thursday morning, with some crews setting off flares during the so far peaceful protest, according to the Jersey Evening Post.

Paris has warned it could cut off power to the island, which receives 95% of its electricity from France through three undersea cables, in retaliation for the fallout.

A Ministry of Defence spokesman said: “HMS Severn and HMS Tamar are deploying to Jersey to conduct maritime security patrols.

“This is a strictly precautionary measure and has been agreed with the Jersey Government.”

A Downing Street spokesman added: “The Prime Minister and Chief Minister stressed the urgent need for a de-escalation in tensions and for dialogue between Jersey and France on fishing access.

“The Prime Minister underlined his unwavering support for Jersey.

“He said that any blockade would be completely unjustified.

“As a precautionary measure the UK will be sending two offshore patrol vessels to monitor the situation.

“They agreed the UK and Jersey Governments would continue to work closely on this issue.”

Speaking to BBC Newsnight on Wednesday, Mr Gorst said: “We take these threats from both Paris and the French fishermen very seriously.

“They are disproportionate to the issues that are being experienced in the post-Brexit trade licensing issuing.”

The row began after the island implemented new requirements under the terms of the UK-EU trade deal for boats to submit evidence of their past fishing activities in order to receive a licence to carry on operating in Jersey waters.

Mr Gorst, however, said the island is not seeking to bar boats which have historically fished in Jersey waters and insisted the dispute can be resolved amicably.

He said that of the 41 boats which sought licences under the new rules last Friday, all but 17 had provided the evidence required.

“The trade deal is clear but I think there has been some confusion about how it needs to be implemented, because we absolutely respect the historic rights of French fishermen to fish in Jersey waters as they have been doing for centuries,” he said.

“I do think a solution can be found.

“I am optimistic that we can provide extra time to allow this evidence to be provided.”