Photo taken on March 18, 2019 shows "Hands Across the Divide", a sculpture in Derry, a border city in Northern Ireland, the United Kingdom.(Xinhua/Han Yan)

EU's Tusk stands by the Brexit backstop, accusing that those against it and proposing no realistic alternatives "in fact support reestablishing a border. Even if they do not admit it."

BRUSSELS, Aug. 20 (Xinhua) -- The President of the European Council Donald Tusk hit back at British Prime Minister Boris Johnson over his remarks on "backstop", saying ditching the so-called Brexit backstop without an alternative was in fact supporting reestablishing the Irish border.

Tusk said in a tweet on Tuesday that "the backstop is an insurance to avoid a hard border on the island of Ireland unless and until an alternative is found. Those against the backstop and not proposing realistic alternatives in fact support reestablishing a border. Even if they do not admit it."

British Prime Minister Boris Johnson makes his first statement in the House of Commons in London, Britain, on July 25, 2019. (Jessica Taylor/UK Parliament/Handout via Xinhua)

Johnson has said the backstop, a position of last resort to maintain a seamless border on the island of Ireland -- between the Republic of Ireland, an EU member state, and Northern Island, part of the United Kingdom -- is unacceptable.

But the EU has long maintained that backstop must stay so as to ensure free movement and no hard border on the island of Ireland which is central to the Good Friday Agreement that has guaranteed peace on the island of Ireland.