French government braces for legal challenges to new tactics, involving extra police, boats and drones

British taxpayers will be expected to contribute more money to stop irregular migration as the French government prepares to halt small boats carrying asylum seekers even if they are already at sea.

It is understood there will be extra costs associated with the scheme to tackle boats within 300 metres of the shore – including paying for police, boats and drones – which the UK will be asked to share with France.

The development comes as a refugee charity that successfully intervened to stop the UK sending boats back to France said it would explore legal avenues to stop the latest tactic. It is understood the French government is braced for court challenges.

Home Office officials confirmed on Wednesday that the French government hoped to launch interventions in the Channel and in nearby waterways in July. It follows increasing use by traffickers of “taxi boats”, which pick up asylum seekers a few hundred yards from the shore before taking them to the UK.