Sinn Fein has given a "cautious and qualified" welcome to the agreement on the Irish border post-Brexit.
Party president Gerry Adams said many questions remained without answer.
"Brexit is the greatest threat to the economies of this island in generations," he said in Dublin.
"Today's communique does not set the final deal on Brexit.
"The communique sets out broad principles. These have been assessed by the Irish government as sufficient progress to allow the Brexit process to move into the next phase of negotiations on trade.
"While the communique recognises the unique and special circumstances surrounding the issue of the Irish peace process, the Good Friday Agreement and the border, it does not address key areas of concern for many citizens - especially nationalists living in the north and citizens in the border region.
"The insistence by the British that Britain and the north must leave the customs union and the single market presents a real and live danger which cannot be understated.
"This also contradicts the British Prime Minister's claim that there will not be a hard economic border.
Mr Adams said he had concern at the suggestion Northern Ireland would no longer be subject the jurisdiction of the European Court of Justice.
He added: "While today's communique represents some progress there are many unanswered questions around key issues and the Irish government must remain focused and vigilant.
"Sinn Fein is also very mindful that this Brexit process is a work in progress.
"Our experience through years of agreements with Britain is that the devil is in the detail."