Brexit: Michel Barnier diaries outline struggles with DUP
The EU's former chief Brexit negotiator says he found it "difficult to stay calm" while meeting the DUP's Arlene Foster and Diane Dodds.
Michel Barnier has published diaries which he kept during the negotiations.
He recounts a meeting with a DUP delegation in Brussels in October 2018 which focused on the backstop.
Mr Barnier writes of his frustration, saying the DUP "oppose everything" and "don't want to hear about the concrete proposals we are making".
He also assessed that Mrs Dodds - the party's MEP at the time - and Mrs Foster "don't like each other and it shows".
He says they tried to outbid each other to "launch slogans and ready-made phrases".
First Minister Arlene Foster told BBC News NI that Mr Barnier's judgement on this occasion was "flawed on many levels".
"A man of Michel Barnier's experience should display a little bit more depth," she said.
Mr Barnier is not entirely negative about the two women in the diary entry however, describing Mrs Dodds as "elegant and competent" and Mrs Foster as "precise and pragmatic in her questions".
Irish border concerns
In the same October diary entry Mr Barnier has warm words for the Ulster Unionist Party's former MEP Jim Nicholson, describing him as a man he likes because of his sincerity.
The book, The Grand Illusion; the secret journal of Brexit 2016-2020, was published in French on Thursday.
Mr Barnier goes into some detail about conversations he had with the Irish government about what would happen with the Irish border in the event of a no-deal Brexit.
Mr Barnier describes a meeting in February 2019 with the then-Taoiseach Leo Varadkar and EU Commission President Jean Claude Juncker.
He writes that other EU member states were sensitive on the issue of the single market, which was directly linked to the border.
He recalls stating: "We must be clear between us. Controls to protect the single market must be put in place somewhere.
"Either around the island, or on the interior of the island. Or on the continent, which has the risk of excluding Ireland from the single market, which we don't want."
He says that at that time the Irish calculation was that even in the event of no-deal, the UK would ultimately agree to some form of Irish Sea border checks.