Keir Starmer has lashed out at the mess Tories have made of Brexit - saying there's "no point in pretending everything is working fine".
The Labour leader accused the Government of "ducking hard conversations" and warned competitors on the continent are "nicking our dinner money".
It comes ahead of Rishi Sunak meeting European leaders for crunch talks at the European Political Community summit in Moldova on Thursday.
Mr Starmer dismissed the Brexit deal as "paper thin" - but ruled out any moves that would see the UK return to the EU under Labour.
He also claimed the Tories had been "ducking hard conversations".
Writing in The Express, Mr Starmer fumed: “There is no point pretending everything is working fine.
"The paper-thin Tory deal has stifled Britain’s potential and hugely weighted trade terms towards the EU.
"Every day it isn’t built upon, our European friends and competitors aren’t just eating our lunch – they’re nicking our dinner money as well.”
He said debates about returning to the single market, the customs union and once again having freedom of movement are "in the past".
Mr Starmer claimed problems such as driving down food prices and stopping small boat crossings can be solved outside the EU.
But he added: “Pretending everything is going fine or ducking hard conversations will see Britain miss opportunities and slip behind our competitors.”
As The Mirror reports today, Labour has savaged the “mess” of the UK’s first post-Brexit trade deals which came into force today.
In a stark warning, Shadow International Trade Secretary Nick Thomas-Symonds urged ministers to step up support for exporters.
The Labour MP has written to Business and Trade Secretary Kemi Badenoch about “significant concerns” raised by the Australian and New Zealand free trade agreements.
He told her: “It is in the hands of your Government to act now.”
The Labour frontbencher highlighted warnings that have been raised by British farmers who say the deal will “heap further pressure” on them.
“When it comes to agriculture, it appears that the Australians have achieved all they have asked for and British farmers are left wondering what meaningful benefits have been secured for them,” the National Farmers Union told a parliamentary inquiry into the Australian agreement.
"There is little in this deal to benefit British farmers. This will just heap further pressure on British farm businesses already facing serious challenges."
George Eustice - the minister who helped negotiate the trade deal with Australia - has even admitted it "was not actually a very good deal" as the UK "gave away far too much for far too little in return".
Mrs Badenoch said: "Today is a historic moment as our first trade deals to be negotiated post-Brexit come into effect.
"Businesses up and down the country will now be able to reap the rewards of our status as an independent trading nation and seize new opportunities, driving economic growth, innovation and higher wages."
