LONDON/LE HAVRE, France, Oct 29 (Reuters) - British Prime Minister Boris Johnson will meet French President Emmanuel Macron this weekend amid a row over post-Brexit fishing rights in which France has seized a British boat and London has threatened to board French trawlers.
The flare-up is part of a wider dispute over post-Brexit trade arrangements between Britain and the European Union that could severely disrupt cross-Channel trade and further undermine British-French relations if it spins out of control.
Johnson's spokesperson said the prime minister and Macron were expected to meet on the margins of the G20 summit of the world's 20 biggest economies on Rome on Saturday and Sunday.
"He will discuss a range of issues," he added, without giving details.
France remained a close and strong ally of Britain, he added. France did not immediately comment on his remarks.
France said this week it would impose sanctions on Britain if London does not allow more French trawlers to fish in UK waters, and it detained a British scallop dredger.
French Agriculture Minister Julien Denormandie said earlier on Friday there had been no progress in talks on granting more licences for French vessels to fish in UK waters, and said it was right for France to prepare sanctions against Britain.
Facing the threat of extra customs checks on British goods and potentially higher energy tariffs from France if talks fail, British Environment Secretary George Eustice said: "Two can play at that game."
"Obviously it's always open to us to always increase the enforcement that we do on French vessels, to board more of them if that's what they're doing to our vessels," he told BBC television.
THREATS AND COUNTER-THREATS
The Cornelis Gert Jan scallop dredger was escorted to the northern French port of Le Havre overnight on Wednesday after its crew failed to prove it was allowed to fish in French territorial waters, French officials said.
British officials said it had the correct documentation. The local prosecutor's office said the vessel's skipper will be called to appear before a court in Le Havre in August, 2022.
Britain's departure from the EU last year deepened strains in its relations with France, and negotiations on fishing rights proved long and difficult even before it left the bloc.
France says Britain has refused to grant its fishermen the full number of licences to operate in British waters that France says is warranted. Britain says it is issuing licences to vessels that meet its criteria.
France has threatened to ban British fishing boats from unloading in French ports, carry out additional licence checks on British vessels, tighten controls of trucks, reinforce customs and hygiene controls and raise power tariffs.
France's ambassador to London has been summoned to explain his country's actions.
Britain's Brexit minister, David Frost, was due to hold talks in London on Friday with Maros Sefcovic, a vice-president of the EU's executive body.
Some British officials portray France's defence of its fishermen as an attempt by Macron to show he is looking after their interests before an election in April in which he is expected to seek a new term.
Johnson can also ill afford to look weak on fishing rights after leading the campaign to leave the EU and promising that leaving the EU was in voters' interests.
Fishing makes a small contribution to the French and British economies but is a lifeline for some coastal communities.
Reporting by Costas Pitas, Paul Sandle and William Schombergin London; Sarah Meyssonnier in Le Havre; Layli Foroudi, Juliette Jabkhiro in Paris; Writing by Timothy Heritage; Editing by Angus MacSwan