Two Navy ships will be sent from the UK to Jersey amid an ongoing row between the island and France over post-Brexit fishing rights and concerns about the prospect of a blockade.

Two offshore patrol vessels will “monitor the situation” after French maritime minister Annick Girardin warned on Tuesday that the country was ready to take “retaliatory measures”, after accusing the Channel Island of dragging its feet over issuing new licences to French boats.

An MoD spokesman said on Wednesday: “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.”

It is understood that the ships are due to arrive on Thursday.

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

A Downing Street spokesman said: “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.”

The UK and Jersey have already criticised France for making “disproportionate” threats after Paris warned it could cut off electricity to the island.

The row has come 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.

A UK Government spokesman earlier said: “To threaten Jersey like this is clearly unacceptable and disproportionate.

“We are working closely with the EU and Jersey on fisheries access provisions following the end of the transition period so trust the French will use the mechanisms of our new treaty to solve problems.”

Mr Gorst told the BBC Radio 4 Today programme: “This is not the first threat that the French have made to either Jersey or the United Kingdom since we are into this new deal.

It would seem disproportionate to cut off electricity for the sake of needing to provide extra details

“It would seem disproportionate to cut off electricity for the sake of needing to provide extra details so that we can refine the licences.”

On Wednesday Mr Gorst held talks with Marc Lefevre, the president of the La Manche region of northern France, on the “difficult set of issues relating to fishing licences”.

“There are a number of important matters which we will continue to work through,” he said.

Jersey receives 95% of its electricity from France through three undersea cables.

Ms Girardin told the French parliament that it gave Paris the “means” to act against the island if the issue could not be resolved.

“Even though I am sorry that it has come to this, we will do so if we have to,” she said.

Mr Gorst, however, said the island was not seeking to bar boats which had historically fished in Jersey waters and insisted the dispute could 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.”

He said the Jersey government was now seeking permission from London and Brussels to speak directly with the French fishermen concerned to resolve the issue.