TEHRAN - Britain’s Prime Minister Boris Johnson has refused to rule out triggering trade dispute action next week in a bitter fishing row with Paris, while French President Emmanuel Macron has told Johnson to “respect the rules.” Macron also went further to question Britain's "credibility.”

Johnson also expressed his concerns "about the rhetoric from the French government,” saying, it does "not appear to be compatible with the UK-EU Trade Co-operation Agreement (TCA) or wider international law.” He added "If there is a breach of the treaty or we think there is a breach of the treaty then we will do what is necessary to protect British interests.”

Both leaders have held a meeting to discuss the escalating tensions between the two countries that culminated with France detaining a British fishing vessel and the UK summoning the French ambassador. 

Following the meeting, the British Prime Minister’s spokesman says no measures had been agreed saying, "It's down to France to decide if they want to step away from the deeply concerning threats. We are not seeking to escalate this. We would welcome it if they de-escalate and withdraw the threats they have made. [But] it will be for the French to decide."

The official statement on behalf of Boris Johnson says he had "reiterated his deep concern over the rhetoric emanating from the French government in recent days, including the suggestion by the French prime minister that the UK should be punished for leaving the EU.”

It further said Johnson had "expressed his hope that the French government would de-escalate this rhetoric and withdraw their threats [of taking further action again British fishers near French waters]."

However, the head of the ports of Calais and Boulogne Jean-Marc Puissesseau, says he had already received instructions to stop British fishers from unloading in Boulogne from Tuesday while the border authorities at Calais would enforce tougher controls on goods-laden lorries.

Speaking to British media he warned that “It will be a drama, it will be a disaster, it will be a chaos in your country because the trucks will not cross, it will be chaos at the ports … It has reached a ridiculous point, I would say.” He has urged “the British and [the French] find an agreement, we find a solution to get out of this point.”

This week, tensions escalated when a British fishing vessel was detained and escorted to a French port after French officials said it did not have the correct papers. Paris has said it could begin to impose targeted measures from Tuesday, including heightening some checks, if the UK does not provide the right amount of fishing licenses for French boats. 

Reports emerging from the UK say French courts have demanded a £125,000 “ransom” for the release of the British fishing vessel detained in the Le Havre port. The Scottish-registered Cornelis Gert Jan is accused of not having a valid license to fish in French waters.

Its unnamed captain has been charged with “acts of unauthorized sea fishing in French maritime salt waters” and ordered to appear in court. He faces £63,000 in fines but sources said an eye-watering bail of £125,000 has been set to ensure he returns to face trial. Owners the company that’s own the vessel have reportedly been ordered to pay the amount before a judge releases it. 

The company insists the vessel had the correct license and is being used as “another pawn” in the bitter dispute between France and the UK.

In France, Monday is a bank holiday so the eight-member crew cannot leave the country until Tuesday at the earliest. One of them has told British media “We’ve been told we are not leaving this weekend. We just want to get out of here.”

Paris has warned London it must grant more licenses for French boats to fish in British waters by Tuesday or face border and port sanctions. At the same time, the UK has told France that, if it does take further action, then it is prepared to kick-start legal proceedings, arguing that Paris will have violated the terms of the trade agreement with the European Union.

In an interview with the British Financial Times newspaper, Macron said the row was a test of the UK’s credibility saying, “when you spend years negotiating a treaty and then a few months later you do the opposite of what was decided on the aspects that suit you the least, it is not a big sign of your credibility.”

A series of angry statements from the British Brexit minister David Frost also underlined how seriously London was taking the situation. It followed a letter sent by French Prime Minister Jean Castex to European Commission president Ursula von der Leyen, that the UK should be shown "it causes more damage to leave the EU than to stay in.” Frost has described the letter as "very troubling."

He also warned the European Union it would be "in breach of its obligations" under the post-Brexit trade deal with the UK if Paris carries out its threats to block British boats from landing their catch at French ports while tightening checks on vessels.

Frost has repeated his assertion that the UK was prepared to commission legal action as a result of the fishing dispute. In a series of statements, the Conservative peer rallied against comments made by Castex.

Frost says, "to see it expressed in this way is clearly very troubling and very problematic in the current context when we are trying to solve many highly sensitive issues, including on the Northern Ireland Protocol. 

"This is all the more so as the threats made by France this week to our fishing industry, to energy supplies, and to future co-operation... unfortunately form part of a pattern that has persisted for much of this year.” 

He also says, "as I set out yesterday to (European Commission vice-president) Maros Sefcovic, these threats, if implemented on November 2 would put the EU in breach of its obligations under our trade agreement. So, we are actively considering launching dispute settlement proceedings as set out in Article 738 of the TCA (trade and cooperation agreement."

It comes as fears grow the UK and France have less than 48 hours to reach an agreement over fishing rights before the French impose restrictions at their ports.

At the center of the dispute are the licenses for boats, which are issued only if the vessels can demonstrate a history of fishing in British waters.

Fishing rights, which has dogged Brexit talks for years, holds huge political importance to both sides, and the row, if not resolved, could trigger the beginning of the dispute measure in the Brexit trade deal. Any such move would likely involve a demand for compensation or more seriously; a suspension of obligations.

French authorities have been further concerned because 55 boats applying to fish in the waters off Jersey Island have been turned down by the island’s government because of a lack of evidence that they have been fishing there for 10 consecutive days in any of the past three years.

With an election in April in which Macron is expected to seek a new term, some British officials believe he is seeking to look tough to appeal to voters back home. This is while some European diplomats see Johnson's government as likewise taking a firm stance to please Brexit supporters.

However, the situation appears more serious with British Foreign Secretary Liz Truss summoning the French ambassador to the UK to challenge the envoy over France's stance.