Darmanin met with UK Home Secretary Priti Patel on Wednesday to discuss the surge of illegal migrant boats through the Channel during warm weather last week. London is accusing Paris of failing to curb the migrant sea transit according to a July deal for which it was paid 54 million pounds ($75 million). And on Thursday, several British media reported, citing government sources, that Patel ordered the UK border patrol to turn boats back.
"France will not accept any practice contrary to the Law of the Sea, nor any financial blackmail. Great Britain's commitment must be kept. I made it clear to my counterpart @pritipatel," Darmanin tweeted.
Friendly relations between the two states should not be harmed by such "postures," he added.
On Wednesday, UK Prime Minister Boris Johnson said that his government will use "every possible tactic at our disposal" to stop the illegal sea arrivals.
Some 13,500 migrants have crossed the English Channel this year so far, the latest boat arriving on Monday and packed with 785 people, according to media reports.