The ex-French foreign minister has been appointed by European Commission president Jean-Claude Juncker to handle Brexit talks on behalf of the bloc’s unelected bureaucracy.
On Tuesday, Mr Barnier gave his first press briefing since being handed the role in July, insisting it is “too soon to talk about the details of Brexit”.
But, outlining a timescale for Brexit negotiations, Mr Barnier said talks could begin within weeks of Theresa May triggering Article 50 by the end of March next year.
Mr Barnier said a draft deal could then be agreed by October 2018, giving enough time for the European Council, European Parliament and Britain’s own Parliament to authorise a Brexit agreement before the end of the two-year Article 50 timescale at the beginning of April 2019.
He said: “We are entering unchartered waters. The work will be legally complex and politically sensitive and will have important consequences for our economies and for our people on both sides of the Channel.”
Mr Barnier has recently begun visiting all 27 remaining EU member states to gauge opinion on Britain’s pending departure, as well as listening to the demands of the European Parliament.
He described how “four main ideas” had informed the Commission’s preparations for Brexit talks, with a warning to Britain not to try and play member states off against each other during negotiations.
Mr Barnier said: “Unity is a strength of the EU. President Juncker and I are determined to preserve the unity and the interest of the EU 27 in the Brexit negotiations. This determination is shared by all governments.”
He also presented the Commission’s hard-nosed approach to Brexit talks, telling Britain a non-EU country “can never have the same rights and benefits” as an EU country “since they are not subject to the same obligations”.
Mr Barnier repeated the EU’s mantra that negotiations will not begin until Article 50 notification, as well as reminding Mrs May the bloc’s four fundamental freedoms – including freedom of movement rules – cannot be negotiated if Britain wants to remain a member of the EU’s Single Market.
He said: “The Single Market and four freedoms are indivisible. Cherry picking is not an option.”
Despite the shock of the Brexit vote, Mr Barnier told EU officials to “keep calm and negotiate”.
Confusingly, the EU has three chief Brexit negotiators in total, amid a power struggle between the Commission, European Council and European Parliament.
Both the Council – made up of EU heads of government – and Parliament – made up of elected MEPs – have appointed their own lead negotiators ahead of Article 50 exit talks.”
Mr Barnier was recently attacked as “inhumane” by Tory MPs over his hardline stance not to begin any informal discussions with Britain until Article 50 is invoked.
Leading Brexit-supporting MPs have called for the EU to assure British nationals currently living on the continent their rights will be protected post-Brexit, which would allow Mrs May to guarantee the rights of EU nationals currently living in Britain.
But Mr Barnier, after a meeting with Mrs May’s Brexit Secretary David Davis, recently posted on Twitter: “No negotiation without notification. My work is now focused on EU27. #Brexit.