The former EU Brexit negotiator accused the UK Government of acting like “pirates” and warned it must be careful not to “sacrifice” its relations with the bloc. But he is known to have lost respect among some figures by casting aside aspects of the EU’s power during his French presidential run – which he went on to lose.

       Mr Barnier passed a message onto Mr Johnson during an interview with Franceinfo, focusing heavily on the issue of post-Brexit fishing rights.

       He accused British ministers of “not respecting” their agreement with the EU on fishing – of behaving like “pirates” in some areas – by not granting enough licences to French fishermen.

       The European Commission, he said, should do more to ensure more licences are granted.

       But on top of this, Mr Barnier insisted the Prime Minister and his Government must work harder towards maintaining a good relationship with the EU because “we have so much to do together”.

       He said: “Mr Johnson has to be careful about the quality of our future relations because this is at stake.

       “I think Mr Johnson has to be careful not to sacrifice the future of our EU-UK and France-UK relationship. We have so much to do together."

       He added: “We need good Franco-British cooperation and the quality of that cooperation depends on the British respecting their signature and their commitments.”

       Mr Barnier’s message come in spite of his diminished position following his recent electoral defeat.

       READ MORE: EU denies banning Crown stamps on UK pint glasses

       His political adviser, Daniel Fasquelle, said in October that “Barnier mania” was taking over the political atmosphere. He added: "There is a snowball effect."

       But the support soon dried. Mr Barnier was knocked out of the race to become France’s next President in December after he failed to beat his party’s counterparts in the primary.

       He came third in this round with 23.93 percent, putting him behind fellow Les Republicains politicians Eric Ciotti (at 25.59 percent) and Valérie Pécresse (25 percent).

       Through his campaign, he argued the EU should hand some powers back to France.

       DON'T MISS:

       Ireland fury as Republic 'lumped into' same group in poll [REPORT]

       Patel urged to take action over Channel strike plans [OPINION]

       Macron on brink of election drubbing after jibe at unvaccinated [REVEAL]

       Despite his lecturing to Mr Johnson, this position appears to have damaged his own relations with numerous figures.

       After he lost the primary, Eurasia Group director Mujtaba Rahman showed little remorse.

       He said: “Michel Barnier is out. He trashed and compromised his European principles for nothing. How sad. Serves him right."

       But Mr Barnier insisted that, despite his loss, he was “proud to have run a dignified and respectful campaign”.

       Additional reporting by Maria Ortega.