Illegal boat migrants have begun carrying firearms across the English Channel, French authorities have reportedly warned Britain’s National Crime Agency.

On what is believed to have been a record day for illegal crossings of the Channel on Saturday, French officials alerted the UK’s equivalent to the FBI of at least one vessel possibly carrying firearms.

Potentially backing up the intelligence, a sailor who was in the water on Saturday told the Daily Mail that he witnessed a boat with thirteen men and a woman in a white hijab crouching around a tarp in the back of the vessel.

“I have seen hundreds of migrant vessels in the Channel. I have never seen this before,” he told the paper.

“They were trying to hide something. The mystery tarpaulin was not being used to protect them from seawater as it was at the back of the boat,” the sailor added.

A maritime conversation overheard on the public airwaves used by boats in the English Channel also heard a lifeboat crewmember saying: “It’s very odd, I have to say.

“They are very reluctant to look at us. It’s all heads down in the boat. There’s something funny about this one.”

It is not currently known what became of the suspicious boat, or indeed if any firearms were seized on Saturday by UK border officials. The National Crime Agency said that it would not comment on “intelligence”, including whether or not weapons were found among the migrants.

It is not the only mystery surrounding the migrant landings on Saturday, as the Home Office has at the time of this reporting still refused to confirm how many migrants landed.

Reports have suggested that as many as 800 illegals may have landed on Saturday, which if true, would represent a record tally for a single day.

Brexit leader Nigel Farage questioned the purpose of the secrecy, writing on Sunday evening: “The Home Office have so far refused to release any official figures for migrant crossings yesterday. What are they hiding?”

The massive waves of migrants on Saturday overwhelmed Britain’s Border Force, with some boats passing them by in the Channel and reaching the shores without intervention.

Illegal aliens were witnessed absconding into the countryside and walking along the A20 motorway towards London. Some were also seen walking towards the Folkestone railway station.

August, which is on pace to be another record month for illegal crossings of the Channel, has seen a confirmed 2,184 migrants land in 70 boats. This figure does not include the potential record arrivals on Saturday.

The pace of illegal migration has been bolstered by people-smuggling gangs using larger and often unseaworthy rubber boats.

According to a report in The Sun, human trafficking gangs are earning as much as £700,000 per boatful of migrants. The fees charged for migrant crossings have soared to an astounding £20,000 per person, with boats often carrying between 30 and 40 people.

French police chief Laurent Hurst told the paper: “For the traffickers, this business is worth more than drug smuggling — you have a very small outlay for a decent-sized boat and that is it.”

While the British taxpayer forked over an additional £55 million to the French to clamp down on migrants setting sail from beaches in Calais and Dunkirk, the crisis has only continued to escalate.

Brexit leader Nigel Farage has predicted that if Priti Patel’s Home Office fails to implement the simple approach of turning the boats back to France, then up to 30,000 illegals may land in Britain by the end of the year.

Follow Kurt Zindulka on Twitter here @KurtZindulka