David Davis calling the phase one Brexit deal a "statement of intent" was "unhelpful and undermines trust", the European Parliament's chief Brexit coordinator Guy Verhofstadt has said.
The senior Brussels politican claimed the text signalling sufficient progress has been made to move negotiations on to trade "will now reflect this".
He insisted the agreement be "translated into legal text ASAP", tweeting pictures of two amendments.
After @DavidDavisMP’s unacceptable remarks, it’s time the UK government restores trust. These amendements will further toughen up our resolution. pic.twitter.com/zKfVlJtOi5
— Guy Verhofstadt (@guyverhofstadt) December 12, 2017
One said Mr Davis' comments were a "risk to undermine the good faith that has been built during the negotiatioins".
The other said phase two talks could only happen "if the UK Government also fully respects the commitments it made".
The row broke out after Mr Davis said the deal struck between Downing Street and Brussels last week was not "legally enforcable".
Guy Verhofstadt called for the deal to be legally-binding
Irish government chief whip Joe McHugh quickly shot back that they would "be holding the United Kingdom to account, as will the European Union".
He told broadcaster RTE: "My question to anybody within the British Government would be: why would there be an agreement, a set of principled agreements, in order to get to phase two, if they weren't going to be held up? That just sounds bizarre to me.
"This, as far as we're concerned, is a binding agreement, an agreement in principle."
EU27 ministers are meeting in Brussels on Tuesday to decide the wording for a separate agreement to formally move talks on to future relations with the UK.