Checkpoints on the Northern Irish border are "unavoidable" post-Brexit, according to Michel Barnier, because of the UK’s decision to leave the EU single market and customs union.
"It is important to tell the truth. A UK decision to leave the single market and to leave the customs union would make border checks unavoidable," he said.
Barnier also hit back at David Davis' criticisms of the EU's approach to Brexit talks. The Brexit secretary yesterday accused the EU of being "discourteous" and said publishing proposals to restrict Britain's access to the single market during the transition period was "not in good faith".
Today, Barnier said: "We have not been in the least bit discourteous or vindictive. It is totally foreign to my state of mind. We have to constructive something that is legally sound and that does not lead to uncertainty."
Meanwhile, according to press reports today, Northern Ireland will stay in the Single Market and the customs union after Brexit.
UK negotiators have been warned the EU draft withdrawal agreement will stipulate that Northern Ireland will effectively remain in the customs union and single market in order to avoid a hard border, the Guardian reported.
A draft agreement shows Brussels expects the UK to approve keeping Northern Ireland under EU rule after the transition period comes to an end. Such an eventuality would not go down well with Theresa May's parliamentary partners, the DUP. DUP leader Arlene Foster has previously said she will not accept any regulatory divergence between Northern Ireland and the rest of the UK after Brexit.
An EU document leaked yesterday also revealed that any dispute during the two-year transition period could lead to sanctions against the UK.
In response, Brexit secretary David Davis said: "I do not think it was in good faith to publish a document with, frankly, discourteous language and actually implying that they could arbitrarily terminate in effect the implementation period.
"That's not what the aim of this exercise is, it's not in good faith and we think it was unwise to publish it."
Earlier this week, another set of leaked documents, this time from the UK government, showed Northern Ireland is projected to suffer a 12 per cent hit to its economy in the event of a no-deal Brexit.