A British fishing boat has been in , prompting accusations of "shameful double standards" from . The Lady T, a 10-metre catamaran from Eastbourne, was intercepted on May 22 by the French navy vessel Pluvier and escorted to Boulogne-sur-Mer, where it is now being held. allege it was fishing for whelks without a licence in .

According to , the boat's skipper could face up to one year in prison and a €75,000 (£63,000) fine. The vessel has been barred from leaving port while the investigation continues, and prosecutors are considering whether to confiscate it. The incident has triggered a furious backlash in the UK, just days after the giving EU fishing vessels access to British waters until 2038.

Shadow Home Secretary Chris Philp told The Telegraph: "This shows shameful double standards.

"The French have failed to stop 13,000 illegal immigrants crossing the Channel this year - taking no action whatsoever at sea and often ushering them into UK waters.

"Yet when a UK fishing vessel is in French waters, they are magically able to act. If they can intercept boats, they should start stopping the ones carrying illegal immigrants, as international law obliges them to do."

Nigel Farage, leader of Reform UK, added: "The French can fish up to our six-mile line for 12 more years, and we have no force of law over them. But if one British boat is in a contested area, there is hell to pay."

French authorities say the Lady T was operating illegally in the French Exclusive Economic Zone, off the Somme Bay, without the required licence.

A spokesman for the maritime prefecture said: "This operation demonstrates the vigilance of state services in protecting fisheries resources and their determination to enforce regulations.

"It sends a clear signal to those who might be tempted to fish illegally in French waters."

Philippe Sabatier, the deputy prosecutor in Boulogne, is leading the investigation.

Some crew members have already been interviewed, and a possible boat seizure is being considered under France's maritime code.

A UK Government spokesperson said: "We are aware that on May 22 a UK-registered vessel was detained by the French fisheries authorities. We are supporting a British national and are in touch with the local authorities."