The Foreign Secretary rejected the deadline set by the French president of tomorrow for more small boats to be granted licences for UK waters.
Instead she insisted that it is Paris that is facing time pressure as the government is prepared to launch action over breaches of the post-Brexit trade agreement.
Ms Truss also risked inflaming the dispute as Mr Macron attends the COP26 summit in Glasgow, suggesting he is merely attacking the UK in the hope it helps his re-election chances.
French officials have warned they will bar UK fishing boats from some ports and tighten customs checks on lorries entering the country with British goods from tomorrow unless more licences are granted for their small boats to fish in British.
Other threats have included a ‘go-slow’ at customs and even increased tariffs on energy bills in Jersey. However, the number of boats being given permits has been creeping up, with the UK stressing that those who can prove a history of fishing in waters before Brexit will be allowed to continue.
Foreign Secretary Liz Truss (pictured at COP today) rejected the deadline set by the French president of tomorrow for more small boats to be granted licences for UK waters
Emmanuel Macron (pictured left at the G20) has insisted Boris Johnson (pictured right at the COP summit today) has until tomorrow to back down in the fishing rights dispute
The Cornelis Gert Jan, a British trawler, was seized by French authorities last week at the port in Le Havre
Asked about whether France and the UK had come to an agreement, Ms Truss told Sky News: ‘The deal hasn’t been done, the French have made completely unreasonable threats, including to the Channel Islands and to our fishing industry and they need to withdraw those threats, or else we will use the mechanisms of our trade agreement with the EU to take action.’
She said the action would take the form of using the dispute resolution mechanism under the post-Brexit trade deal to seek ‘compensatory measures’.
‘That is what we will do if the French don’t back down,’ she added.
‘Stop threatening UK fishing vessels, stop threatening the Channel ports and accept we are entirely within our rights to allocate the fishing licences in line with the trade agreement.’
She said she would ‘absolutely’ take legal action in the coming days if France does not back down on threats, saying: ‘This issue needs to be resolved in the next 48 hours.’
Ms Truss said Mr Macron might be making ‘unreasonable threats’ because of the looming election.
‘You might say there’s a French election coming up,’ she said.
In a day of extraordinary briefing as Mr Macron and Boris Johnson attended the G20 summit in Rome, the French premier insisted that the ‘ball is in Britain’s court’ and reprisals are set to go ahead.
In a day of extraordinary briefing, Paris initially claimed that Mr Johnson and Mr Macron had reached a deal on de-escalation during 30 minutes of talks on the margins.
There were no officials or cameras present as the pair tried to reach an understanding one-on-one.
But that version was rejected by Mr Johnson, who stressed that he viewed Mr Macron as a ‘friend’ but they had a ‘wide-ranging and frank’ discussion. ‘On fish I have got to tell you the position is unchanged,’ he said.
Mr Johnson said he was ‘puzzled’ by a letter from French prime minister Jean Castex to European Commission president Ursula von der Leyen, in which according to some translations Mr Castex said the UK should be shown ‘it causes more damage to leave the EU than to stay in’.
At a G20 press conference, Mr Johnson said: ‘On fish, I’ve got to tell you the position is unchanged. And I’ll just say this, for the record. I must say I was puzzled to read a letter from the French Prime Minister explicitly asking for Britain to be punished for leaving the EU.
‘I just have to say to everybody I don’t believe that that is compatible either with the spirit or the letter of the Withdrawal Agreement or the Trade and Cooperation agreement, and that’s probably all I’ll say about that one.’
But Mr Macron said: ‘The ball is in Britain’s court… ‘If the British make no movement, the measures of November 2 will have to be put in place.’
Earlier the PM’s spokesman said it was a matter for France to decide whether to back off the threats.
‘We certainly stand ready to respond should they proceed with breaking the Brexit agreement,’ the spokesman said.
A French aide told Reuters after thee talks: ‘The goal for both the president and the prime minister was to work towards de-escalation.’
French sources told AFP the two sides agreed ‘operational measures’ to take the heat out of the row in the coming days.
What is the fishing row between the UK and France about?
– How did Brexit spark the fishing feud?
When the UK left the EU, it also left the common fisheries policy, which since 1970 has allowed the bloc’s members access to all European waters outside the first 12 nautical miles of each country’s coastline.
The Brexit deal outlined how EU boats could continue to fish in UK waters, but British fishermen would get a greater share of the catch from those domestic waters.
Most of the share is being transferred to the UK this year, and there will be annual negotiations to decide how the catch is shared out going forwards.
– Why has this inflamed tensions with France?
The rollout of the post-Brexit arrangements has caused a row, with Paris accusing the UK of failing to grant permission to every eligible French boat to fish in British waters.
But the UK is adamant that it is following the terms of the Brexit deal which requires trawlers to provide historical GPS data to prove they worked in those waters before Brexit.
Some vessels have been unable to provide that data which has seen their applications for a licence be rejected.
The Government has insisted 98 per cent of all EU fishing licence requests have been granted but France believes it is being shortchanged.
– What is France threatening to do?
French ministers have warned they will block British boats from some French ports and tighten checks on vessels travelling between France and the UK if the fishing licence dispute is not resolved by Tuesday next week.
France’s Europe minister, Clement Beaune, told French TV news channel CNews: ‘We have been extremely patient. Our fishermen have been extremely responsible. And so, from November 2, it’s over. We will engage in dialogue if the British want to, but we are taking retaliatory measures.’
– How has the UK responded?
Environment Secretary George Eustice said the French threats risk breaching the terms of the Brexit deal and EU law.
He warned the UK would respond in an ‘appropriate and calibrated’ manner if they were carried out.
The UK Government is calling for ‘calm’, with the Foreign Office summoning the French ambassador to explain the actions taken by Paris.
– Why was the British trawler detained?
The scallop vessel Cornelis was ordered to divert to the port of Le Havre after the French authorities said it was fishing in French waters without a licence.
The French said that another British trawler had been fined for obstruction after refusing to allow police to board to carry out checks.
The owner of the Cornelis, Macduff Shellfish, said the vessel had been fishing legally in French waters and called on the British Government to protect the rights of British fishermen.