Michel Barnier has dismissed a row with his British counterpart David Davis over the Brexit talks - saying: "My attitude has not been in the least discourteous or vindictive."
The EU's chief Brexit negotiator said draft proposals that would allow the bloc to sanction Britain during the transition period were not an attempt to "punish the UK", after the leaked text sparked fury among Eurosceptics.
Mr Davis, the Brexit Secretary, accused the EU of acting in bad faith and using "discourteous language" in the legal document, which set out proposals to block Britain's access to the single market if it failed to comply with EU rules during the two-year transition.
Speaking to reporters in Brussels, Mr Barnier said: "We never wished to punish the UK - it's totally foreign to my state of mind, and this has been true from the very beginning and this will be true until the very end of the negotiations.
"Quite simply we have to construct a withdrawal agreement which is legally sound and does not give rise to any uncertainty in anyone's mind."
Mr Barnier said he could not understand the "uproar" over the document, in which Brussels sought to "suspend certain benefits" including "participation in the single market" if the UK flouts EU rules.
He said: "There is no wish whatsoever to punish. We are trying to draft an international agreement on a solid basis that can be effectively implemented."
Demands for enforcement powers signal growing fears in Brussels that Britain will not abide by its rules during the two-year period, as suspension of single market access would hit financial services, trade of goods and agreements with airline operators.
Brexiteers were outraged by the leak of the document, fearing that Britain will become a “vassal state” after formally leaving the EU in March 2019.
Mr Davis intervened in the row after a key meeting of Theresa May's Brexit "war Cabinet", when he said it was a "political document" with "frankly discourteous language".
Asked about the claims, Mr Barnier told a press conference in Brussels: "Since the very beginning, quite naturally, I have been objective.
"I have never been aggressive, I am not vindictive, I am not trying to punish anyone.
"I very much regretted the British vote on Brexit, like others, but we respect that vote."
Mr Barnier also fired off a warning to the Government that the EU would deny Britain the Brexit transition period it wants if ongoing disagreements are not resolved.
He said that a transition period was “not a given” and that “there will undoubtedly be a problem” if the UK refused to budge.