British PM Johnson does not regret letter to Macron - spokesman

British Prime Minister Boris Johnson does not regret his letter to French President Emmanuel Macron about tackling the migrant crisis in the Channel and wrote it "in the spirit of partnership and cooperation", Johnson's spokesman said on Friday.

Responding to the letter, Macron told Britain it needed to "get serious" or remain locked out of discussions over how to curb the flow of migrants escaping war and poverty across the Channel.

"This is an issue that we are taking extremely seriously," Johnson's spokesman said of the migrant crisis.

Asked if Johnson regretted sending the letter and posting it on Twitter, the spokesman said: "No ... both the Prime Minister and President Macron have a shared recognition of the urgency of the situation were both facing and you'll see from the tone of the letter this is about deepening our existing cooperation."