Senior Border Force officers have voiced frustration over what they describe as an inconsistent response from French police as migrants continue to make dangerous Channel crossings.

Their concerns came after 752 migrants reached the UK in nine small boats on Wednesday – the highest daily total recorded this year – before four migrants died in separate crossing attempts.

Border Force sources also warned that the criminal gangs organising the journeys are becoming increasingly violent, revealing that an automatic firearm was recently discovered in one of the migrant camps in northern France.

“There is a regular drumbeat of firearms being found,” a Border Force source told The Times.

“They’re used to facilitate the smugglers’ activities — controlling patches, making sure they keep the spaces where they launch the dinghies and for enforcing protection. The gangs controlling the crossings are involved in proper criminality.”

Officials said frustration had grown after French gendarmes took different approaches to two boats that became stranded on the same beach on Wednesday.

In one case, officers did not intervene after a dinghy became grounded, saying they were not authorised to enter the water. Later that day, however, gendarmes waded into the sea to stop another stranded boat.

A senior Border Force source said: “The gendarmes are very cautious. Last year, when they slashed the boats, it led to quite a difficult situation.

“Land-based officers can’t go into the water because they will be criminally responsible if someone dies. Their rules of engagement don’t allow them to enter the water.

“But they did disable that boat last night. It had run aground and was disabled. They will go in and do it depending on the right circumstances.

“It’s quite frustrating because it’s not consistent. There is a degree of latitude and they do go in sometimes when there’s a safe opportunity to do so.”

The French government announced in April that 125 specialist officers would be deployed to tackle small boat crossings, including units trained to intervene in the water.

However, no officers from those specialist teams were present on the beach on Wednesday despite forecasts indicating conditions would be favourable for crossings.

A Home Office source described their absence as “frustrating” and “far from ideal”.

The Home Office said it was “deeply saddened” by the deaths, adding they were “a stark reminder of the dangers posed by criminal gangs exploiting vulnerable people for profit”.

A spokesman added: “We will continue working relentlessly with the French and our partners overseas to prevent these perilous journeys.”