Michel Barnier also doubted whether Britain "fully understood" the consequences of its vote to leave the European Union in March 2019.
He said that Ms May's negotiating position, including abolishing free movement, striking free trade deals and scrapping any role for the European Court of Justice, implied the United Kingdom is leaving both the single market and the customs union.
A Downing Street spokesman said the UK's position was that it would secure "the most frictionless possible trade" between the United Kingdom and the European Union, adding that London's position is clear when asked if Ms May understood the EU's stance.
There's been talk in the highly fluid political scene in Westminster of trying to explore cross-party support for a transitional phase that keeps the United Kingdom in the Single Market and the Customs Union.
Michel Barnier took a tough position on the Brexit negotiations Thursday, warning there will be "negative" consequences no matter what.
"On the European Union side, we made three things very clear: the free movement of persons, goods, services and capital are indivisible". We can not let the single market unravel.
Barnier explained that a "frictionless trade" would only be possible with "the combination of the customs union and the rules of the internal market".
"These consequences are the direct result of the choice made by the United Kingdom, not by the EU".
But Mr Barnier said Mrs May's "red lines" for a future trade relationship meant the United Kingdom was definitely leaving the single market and the customs union.
Despite his ominous tone, Barnier stressed: "There is no punishment for Brexit".
He pointed out that access to the internal market without the customs union, as happens in the European Economic Area, still requires EEA members Norway, Iceland and Liechtenstein to comply with a system of procedures and customs controls; similarly, Turkey's customs agreement with the EU, without access to the internal market, has an implied system of procedures and customs controls as well.
Two weeks ago at the EU Council meeting, European Commission President Jean-Claude Juncker in answer to a question asking if he was clearer now on the United Kingdom position on Brexit snapped back: "no".
Downing Street said the Government did understand the EU's position and was focused on "getting a deal that works for both sides" but acknowledged there were "strong feelings" in Brussels about the result of the Brexit referendum.
The French politician said he was ready for the talks to fail, but said "no deal" would be damaging, especially for Britain, and saw "no reasonable justification" for it. "There is no reason further to worsen the consequences of Brexit".
In its new manifesto the CDU/CSU refers to the relationship as Germany's most important "partnership" outside Europe. Both leaders have a lot to discuss, from the issues of refugees to the counter-terrorism measures.
Keane was reportedly hopeful of a return to former club Manchester United , but they opted to sign Victor Lindelof from Benfica. The Toffees may also conduct further business with Burnley this summer after reports talks have opened over striker Andre Gray.
Ryan killed herself in her home. 'I remember waking up and one Little Loca video had like 900 hits and I was like 'Oh, my gosh. The character was obsessively fawn over men on MySpace as well as how many friends she had on the social site.
He is likely to compete with Nampalys Mendy for playing time alongside Wilfried Ndidi and Danny Drinkwater . Iborra is a defensive midfielder who is powerful in the air and can control the tempo of a game.
The iPhone 4 received much praise, particularly due to the improvement in style with a body of stainless steel and glass. The folks over at OnLeaks and Tiger Mobiles claim to have gotten their hands on an iPhone 8 dummy unit.
Forty-seven percent of the 15 oil market experts say there is more downside risk, but 40 percent say there should not be. The investment bank cited higher-than-expected production from Nigeria , Libya and a swift rebound in US shale output.
"I get exhausted reacting to the president's constant use of Twitter , and I just think he needs to focus on the issues". Crazy Mika ", and claimed she was bleeding from a facelift upon her arrival to Trump's Mar-A-Lago resort at New Year's.
The defending champion pulled out of a planned warm-up match at London's Hurlingham Club due to a hip problem this week. However, his team are keen to play down prospects that Murray will pull out of Wimbledon .
Illinois Ends Two-Year Budget Battle After Chemical Scare
Bruce Rauner's veto, ushering in higher income taxes along with a bit of fiscal certainty the state hasn't had since 2015. The state's finances remain a mess, with over $15 billion in overdue bills because of the budget standoff.
Wildfire north of Breckenridge prompts evacuations
The Sheriff's Office encourages the public to comply with the evacuation order, which is in place for the safety of the public. The base of the ski resort, which includes hotels and restaurants, has not yet been evacuated.
J&K will be benefitted most by GST: BJP
PDP MLA Javid Beg reacted sharply to Rashid's statement followed by BJP members demanding Rashid's suspension. He also read out the provisional GST registration numbers of various businesses owned by Rana and his family.
Takata files for bankruptcy, to be bought by US-based firm
In the US, Takata agreed in January to plead guilty to wire fraud for falsifying testing data and reports provided to carmakers. Takata is expected to use $1 billion of the proceeds to cover its settlement of criminal charges with US authorities.