The European Council President says the Taoiseach will be consulted on the UK's offer on the border before Brexit talks can progress to the next stage.
British Prime Minister Theresa May has been given until Monday to come up with a "final offer" to EU leaders on how to avoid a hard border between the North and the Republic.
Donald Tusk is due to lead a summit of EU leaders in two weeks, where a decision will be made on whether talks should move on to trade and future relations.
He says it is up to the UK to find solutions for the border:
This ultimately means Ireland could block Brexit talks moving on if the UK doesn't come up with an acceptable solution for the border by Monday.
Sinn Fein's Brexit Spokesperson, David Cullinane, says the government shouldn't allow talks to move on unless the UK comes up with workable solutions:
