BORIS Johnson has been accused of engaging in "stupid blame game" after Downing Street claimed the EU had made a Brexit deal "impossible".

Downing Street sources claimed German chancellor Angela Merkel had made clear that an agreement was now "overwhelmingly unlikely".

Following a telephone call with Boris Johnson, she was said to have insisted the Irish must have a veto over Northern Ireland leaving the customs union.

The claims provoked a furious response from European Council President Donald Tusk who accused him of jeopardising the future security of the EU and the UK.

"Boris Johnson, what's at stake is not winning some stupid blame game," he tweeted.

"At stake is the future of Europe and the UK as well as the security and interests of our people.

"You don't want a deal, you don't want an extension, you don't want to revoke, quo vadis?"

Amid the dramatic escalation in the war of words between London and Brussels, there was apparent alarm among some UK ministers at the prospect the Government could withdraw security co-operation with the EU if it tries to stop the UK leaving in a no-deal Brexit at the end of the month.

Northern Ireland Secretary Julian Smith said: "I am clear that any threat on withdrawing security co-operation with Ireland is unacceptable."