Warning the EU's position appeared not to have been "fully understood" by some in London, Mr Barnier said: "I have heard some people in the United Kingdom argue that one can leave the single market and keep all of its benefits".
The EU's chief Brexit negotiator says Britain can not enjoy "frictionless" trade with EU partners after it leaves the union.
Speaking in Brussels on Thursday, Barnier said that it was his "duty" to say that "the decision taken by the United Kingdom to leave the European Union will have major consequences".
To view the full article, register now.
He countered that "a fair deal is far better than no deal" and pointed out Brexit talks were not a classic negotiation, where "no deal" meant reversion to the status quo.
Losing access to the single market would lead to City firms losing "passporting rights", which provide wide-ranging European Union access for UK-based financial services. "But it is not clear whether they have been fully understood across the channel", he added.
Barnier emphasised that this was based on a decision - that he personally regretted - that the British had made: "There is no punishment for Brexit".
He reluctantly put his name to the Remain side in the referendum and fired some lawmakers who backed an amendment in Parliament calling on the government to keep open the option of staying in the bloc's single market and customs union. "But Brexit has a cost, also for business in the EU27, and businesses should assess with lucidity the negative consequences of the United Kingdom choice on trade and investment and prepare to manage that".
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. Pointing out that the cost of Brexit was also a cost for business in the EU27. "And the United Kingdom would have more to lose than its partners", the French former commissioner, said.
Amid talks in British media that United Kingdom prime minister Theresa May would be ready to walk out of talks on the financial settlement - the money the United Kingdom will have to pay as part of its European Union commitments - Barnier insisted that progress will be needed on the three issues "together", before talks on future relations can start.
"The EU already has free trade agreements with 58 countries that are not members of the customs union".
Barnier said: "I have heard some people in the United Kingdom argue that one can leave the single market and keep all of its benefits".
As negotiations will start more than three months after May triggered the 2-year negotiating period, Barnier also warned that "time flies" until 29 March 2019, when Brexit will happen automatically.
Prayers and support for Charlie have been flooding in from across the world, including from Pope Francis and U.S. A USA doctor and a Catholic hospital in Italy both offered to care for Charlie if he can be transferred.
Democratic Assembly Speaker Vincent Prieto opposes the bill and refuses to consider it for a vote, leading to a stalemate. I will not tax them anymore and in my budget overall taxes were decreased. "I've been coming here for 18 years".
Meanwhile, U.S. officials will soon confront the challenge of raising the debt ceiling to continue to fund the government. The increase of 0.25 percentage point raised the rate to between 1% and 1.25%.
Specifically, doctors have claimed that took keep Charlie alive would "continue to cause Charlie significant harm". They are not permitted to take him home, and they say that the hospital is "rushing" to turn off the ventilator.
Tributes honouring her courage and determination to advance women's rights were paid from within France and beyond. Born Simon Jacob in Nice in 1927, Veil was 17 years old when she was sent to Auschwitz concentration camp.
An evacuation standby has been put in place for the roughly 40 homes in the Gold Hill neighborhood. [Updated: June 5, 7:25 p.m. The Summit County Emergency Management said over 450 homes were ordered to evacuate, but no homes have been destroyed.
On the inventory side, USA oil inventories fell by 0.8 per cent MoM in June to 509.2 million but were 3.1 per cent higher YoY. In a separate note on Wednesday, Goldman cut its WTI forecast for the next three months by $7.50 a barrel to $47.50.
Once a deal is concluded, Iborra will be allowed to return to Sevilla to bid a public farewell to fans. Sevilla added that the move for the Spaniard is subject to a medical and personal terms being agreed.
The Toffees may also conduct further business with Burnley this summer after reports talks have opened over striker Andre Gray. Burnley are resigned to losing one of their top performers of last season, with Keane entering the final year of his contract.
Trump for his offensive words and can only hope that the women who are closest to him will follow their examples". He referred to her co-host and fiance Joe Scarborough , a former Republican US congressman, as "Psycho Joe".
Who Won Nathan's Hot Dog Eating Contest 2017?
And true to form, " Joey the jaws" did not disappoint! Both he and Stonie are from San Diego, California. Meanwhile, for those who find this sort of hot dog overindulgence objectionable, you're not alone.
Demare takes Tour stage amid crashes
Sagan's bodyguard told journalists that the world champion had been destabilised in the sprint finish by another rider. Cavendish was pushed off his line then tried to shoot a gap that wasn't there.
Air Asia X plane makes Emergency landing in Brisbane
The Airbus, which was carrying 345 passengers and 14 cabin crew, flew for another hour before landing safely in Brisbane . As the mid-air confusion unfolded, the pilot ordered passengers to turn off all electrical devices and cameras.
Navy destroyer sails near disputed island claimed by China
So by sailing within that distance of Triton, the Stethem dismissed China's claim to both the island and the waters around it. The destroyer came within 12 miles of Triton Island - which is claimed by China - much to the fury of Beijing.
JJ Redick agrees to one-year $23 million deal with 76ers
Entering the weekend, their top priorities were Denver forward Danilo Gallinari, Utah's Ingles and San Antonio's Jonathan Simmons. He averaged 15 points in 78 games last season for the Los Angeles Clippers and shot 42.9% from deep.
Utah Jazz on verge of landing Ricky Rubio
Teague averaged 15 points and almost eight assists per game last season with the Indiana Pacers last season. That's more money per year than the Ricky Rubio deal, but Rubio would likely command more money next year.
Mother who gives birth on a plane tells her story
Once the plane landed, mother and baby were taken to Louisiana's Ochsner Medical Center and are both doing well, Spirit said. The nurse clamped down on the umbilical cord with some rubbery straps they found on the plane, she added.
French Far-right's Le Pen Faces Funding Scandal Probe
The formal investigation of Le Pen comes less than two weeks after she won a seat in the French National Assembly. In February, the European parliament said it would start docking Le Pen's pay unless she paid the money back.
Serena asks McEnroe for respect after comparison
However, John McEnroe , a retired tennis player considered one of the greats, doesn't seem to have his head around this yet. The world number one female played in the game instead and lost to Riggs 6-2 6-1. 'I don't know what to do with a baby.