BOULOGNE-SUR-MER, France, Nov 1 (Reuters) - People who earn a living from fishing in the English Channel battened down the hatches on Monday for an escalation of a Franco-British row over fishing licences that they anticipate will be costly on all sides. France alleges Britain is not honouring a post-Brexit deal on access to British fishing grounds and has said that from midnight (2300 GMT) on Monday it will retaliate by stepping up checks on trucks coming from Britain and barring British trawlers from docking in French ports. Olivier Leprêtre, president of the regional sea fishing committee for northern France, said he had advised his group"s members to steer clear of British waters, in case they were caught up in tit-for-tat British measures. Tracking data for marine traffic in the English channel on Monday afternoon showed that most of the French fishing fleet were staying close to their shorelines. British trawlers were also staying in their own sector. Lepetre said France needed to take tough action on Britain, but his members also worried about collateral damage from a worsening row. Britain"s government on Monday issued its own threat to France, telling Paris it had 48 hours its planned retaliatory measures, or face legal action. read more Stephane Pruvost is boss of sea food processing firm JP Marée, one of several in the port of Boulogne which import part of their raw materials from Britain. He said he feared disruption to his supply chain on Tuesday if France follows through on threats to step up checks on trucks entering France from Britain at the port of Calais, and arriving in Boulogne. "Is blocking imports the solution?” he asked, in an interview with Reuters. Referring to French President Emmanuel Macron, he said: “Macron isn’t aware of the effects of all of this. We are only listening to the voice of the fishermen and not anyone in any other stage of the chain." Stephane Fournier, a 44-year-old fisherman in Boulogne-sur-Mer, is among dozens waiting for Britain to issue his vessel with a licence to fish in its waters. He said France had to retaliate against Britain, even if there is blowback for French fishing crews. “I prefer losing one month’s salary to losing our livelihood, our way of life,” he said. The row being played out between London and Paris over fishing licences was, he said, a "political game with pride on each side and we are in the middle watching the match".