The EU's chief Brexit negotiator said on Thursday he is ready to speed up talks with Britain on its exit from the bloc as he voiced concern about progress and London's proposal for the border with Ireland.
Often accused of rigid thinking on Brexit, the European Union in the paper echoes Britain in calling for "flexible and imaginative solutions" on Ireland, "including with the aim of avoiding a hard border".
Britain has rejected an Irish demand for a role in running Northern Ireland if parties there fail to revive a devolved power-sharing government.
He was expected to say: "In my view the only way of resolving the border conundrum is for Northern Ireland to be within the same customs union and single market as the Republic - either Northern Ireland alone or preferably with the whole of the United Kingdom". "This will not happen".
'For example, on Northern Ireland it would be helpful to our shared objectives on avoiding a hard border to be able to begin discussions on how future customs arrangements will work.
In Dublin, an Irish government statement called the European Union paper a "timely and helpful input" bolstering principles for future negotiations.
Under the plans, people will be able to work, go to school and receive medical treatment either side of the Irish border.
Negotiations to extricate Britain from the European Union have seen a slow start and the EU's chief negotiator Michel Barnier has repeatedly warned that time is running out to answer complex questions before Britain is due to leave in March, 2019.
The Labour MSP added: " The talks do not appear to be making as much progress as had been expected by this point of time. Creativity and flexibility can not be at expense of integrity of the single market. The paper stressed that there should be no return to a hard border "as a result of any new controls placed on the movement of goods between the United Kingdom and the EU" and that the imposition of new customs barriers within the United Kingdom could not be accepted.
"I am particularly concerned about whether any transitional arrangements can be agreed that allow us to maintain access to the single market in the short-term, and give us time to resolve hard issues for the long-term".
The UK has warned it is European Union single market rules that could force the re-creation of border posts and not British law. "The slogan of Brexit was, 'take back control of our borders.' The British have shown virtually no interest in taking back control of the Irish border, they see that as a problem for the Republic of Ireland and the European Union".