The European Union told British Prime Minister Boris Johnson on Saturday that he must implement the Brexit deal that he signed to ensure the delicate peace in Northern Ireland and that the 27-member bloc was completely unified on that position, Eurasia Diary reports citing News.az.

The United States has expressed grave concern that a dispute between London and Brussels over the implementation of the 2020 Brexit divorce treaty could undermine the 1998 Good Friday peace deal that ended three decades of violence.

After the United Kingdom exited the bloc's orbit on Jan. 1, Johnson has unilaterally delayed the implementation of some provisions of the Northern Ireland Protocol of the deal and his top negotiator has said the protocol is unsustainable.

"The Good Friday Agreement and peace on the island of Ireland are paramount," Ursula von der Leyen said after a meeting with Johnson and European Council President Charles Michel. "Both sides must implement what we agreed on."

"There is complete EU unity on this," she said, adding that the deal had been agreed, signed and ratified by both Johnson's government and the EU.

The 1998 peace deal largely brought an end to the "Troubles" - three decades of conflict between Irish Catholic nationalist militants and pro-British Protestant "loyalist" paramilitaries in which 3,600 people were killed.