His comments came after Brexit minister David Frost told the European Commission that the UK is ready to retaliate if France imposes sanctions next week.
Frost told Commission vice-president Maros Sefcovic that any move by Paris to block access to its ports by British vessels or to cut electricity supplies to the Channel Islands would put the EU in breach of the post-Brexit trade deal it struck with the UK a year ago.
Britain could step up enforcement and checks on EU boats in its waters, as well as launching formal dispute settlement mechanisms in what would be a significant escalation of post-Brexit hostilities.
France’s ambassador to London, Catherine Colonna, was hauled in to the Foreign Office to explain Paris’s stance to Europe minister Wendy Morton.
And Downing Street confirmed that Mr Johnson will speak with Mr Macron personally about the row in a “brush-by” meeting at the G20 summit in Rome, in what amounts to a distraction from his priority of lobbying other leaders for climate action at the Cop26 summit which he is hosting in Glasgow next week.
Speaking to reporters as he travelled to Rome, the PM shrugged off suggestions that the spat could derail his hopes of securing agreement in Glasgow, telling reporters: “There are bigger fish to fry, everybody knows that.”
And he signalled he will take an emollient tone with Mr Macron in the hope of soothing the bust-up, sparked by French complaints that ships which have historically fished in waters off Jersey and Guernsey are being denied licences following Brexit.
The prime minister lavished affection on France as “one of our best, oldest allies, friends and partners”.
He vowed to do “whatever is necessary to ensure UK interests”, suggesting France is in breach of the Brexit trade agreement.
But he added: “The ties that unite us and bind us together are far stronger than the turbulence that currently exists in the relationship.
“That is what I will say to Emmanuel, who is a friend I’ve known for many years.”
The cross-Channel bust-up has been fuelled by the French seizure of a Scottish-registered fishing boat, held by the maritime gendarmerie at Le Havre for two days.
The skipper of the Cornelis Gert Jan has been ordered to appear in court next year to answer charges of operating without a licence in French waters, and is facing a possible maximum fine of €75,000 (£63,000).
But the UK insists that the case is separate from the ongoing dispute over licences. And Downing Street said that 98 per cent of applications by EU boats to fish in British waters have been approved, though numbers are far lower in the Channel Islands.
The prime minister said the UK is “puzzled about what is going on”, as France protests that its fishing vessels have been wrongly denied access to UK and Jersey waters.
But he insisted that it did not indicate a deeper rift between London and Paris.
“There may be people, on either side of the Channel, who think they may have an interest in somehow promoting disharmony between the UK and France,” said Mr Johnson.
But he added: “I don’t think Emmanuel shares that perspective.”
Asked about trade becoming “snarled up”, at a time when UK supermarkets are already short of some goods, he said: “I haven’t heard that from our French friends. I would be surprised if they adopted that approach.”
Speaking after his talks in London with Mr Sefcovic, a UK government spokesperson said that Lord Frost had set out the UK’s concerns about “the unjustified measures announced by France earlier this week to disrupt UK fisheries and wider trade, to threaten energy supplies, and to block further cooperation between the UK and the EU, for example on the Horizon research programme”.
The spokesperson said: “Lord Frost made clear that, if these actions were implemented as planned on 2 November, they would put the European Union in breach of the Trade and Cooperation Agreement (TCA).
“The government is accordingly considering the possibility, in those circumstances, of launching dispute settlement proceedings under the TCA, and of other practical responses, including implementing rigorous enforcement processes and checks on EU fishing activity in UK territorial waters, within the terms of the TCA.”
A European Commission spokesperson said Mr Sefcovic urged the UK to “intensify discussions with the European Commission and France in order to swiftly resolve the issue of pending fishing licences”.
“All French vessels entitled to a licence should receive one,” the spokesperson said.
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