Sinn Fein Leader Mary Lou McDonald and Deputy Leader Michelle O'Neill held a news conference after meetings in Brussels with European Union Chief Brexit Negotiator Michel Barnier.
McDonald also met with members of the European Parliament steering group on Brexit.
"We require, and I believe that we have been given, a very strong commitment that the protections contained within the backstop will be held constand," the Sinn Féin leader said.
She reiterated that it is important Dublin "holds firm on this issue".
McDonald also paid tribute to Barnier and fellow member states’ “genuine” and “steadfast” commitment to protecting the Belfast Agreement.
Barnier did not appear at the meeting.
Watch the full conference in the video player above.