Labour will oppose any Brexit deal in a House of Commons vote if it does not meet "six tests".

In a significant hardening of Labour's position, shadow Brexit secretary Sir Keir Starmer outlined the tests for the Government and EU leaders to meet.

Any deal must offer the "exact same benefits" the UK has from the single market and customs union, and include a strong relationship with the EU, Sir Keir said in a speech at Chatham House in London.

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And he warned that "failure to meet the tests... will of course affect how Labour votes in the House of Commons".

The six tests of the deal are:


:: Does it deliver the "exact same benefits" as the UK currently has as a member of the single market and customs union?

:: Does it ensure a strong and collaborative future relationship with the EU?

:: Does it ensure the fair management of migration "in the interests of the economy and communities"?

:: Does it defend rights and protections and "prevent a race to the bottom"?

:: Does it protect national security and the UK's capacity to tackle cross-border crime?

:: Does it deliver for all regions and nations of the UK?

Sir Keir said: "All of us want the best for Britain. But the stakes are high and the Prime Minister's approach so far does not bode well.

"The Prime Minister should be under no illusion that Labour will not support a deal that fails to reflect core British values and the six tests I have set out."

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The Labour frontbencher backed Theresa May's goal of a comprehensive free trade agreement but argued cooperation in security, science, research, culture and technology should also be retained.

He warned against "increasingly powerful moves on the Government benches to sever our links with Europe", cautioning this "ideologically driven approach to Brexit would be disastrous and divisive".

He said: "The Prime Minister needs to face down these Brexiteers who would distance us from Europe.

"And the clearest way for her to do so would be to agree a strong and collaborative relationship with the EU."

Negotiations will start after Mrs May triggers Article 50 of the EU treaties on Wednesday.

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The Prime Minister has insisted that no deal is better than a bad deal, but Sir Keir said: "The biggest danger currently facing British businesses, jobs and living standards is the chance of the Prime Minister exiting the EU without a deal.

"This is the worst of all possible outcomes.

"The Prime Minister should end this unnecessary uncertainty now by committing to establish appropriate transitional arrangements starting on March 29, 2019 and lasting until a full and collaborative EU-UK treaty can be agreed."