Rachel Reeves has thrown her weight behind the Prime Minister's position on the possibility of deepening ties with the EU, arguing that Brexit left the UK “poorer, weaker and less secure”.

Her intervention comes after remarks by the Prime Minister in recent days fuelled questions about the prospect of Britain returning to the bloc or adopting its freedom of movement rules.

The former chancellor set out her case in The Sunday Times. Writing in the paper, the Labour former Cabinet minister said she welcomes “Andy Burnham’s leadership”.

Ms Reeves, who was sacked as chancellor by Andy Burnham when he took office, said: "I am proud of the progress we have already made in strengthening our relationship with the European Union.

"Brexit has made us poorer, weaker and less secure.

“There is a debate to be had about our future relationship with Europe, and I welcome Andy Burnham’s leadership in facing up to this. No one in the Treasury ever doubted where my instincts were.”

Although Ms Reeves said she believed “Britain’s future lies in the European Union”, she stressed it was “incumbent on supporters of our re-entry to make the argument, demonstrate tangible benefits and to get the next steps right”.

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Mr Burnham wants to lock in deals on food and drink, emissions trading and a youth mobility scheme at a summit with the bloc next month.

He told ministers that the period beyond that would be to “explore options” for the long-term relationship.

Any options on Britain's future relationship with Brussels will eventually be put to the public.

The Prime Minister earlier this week warned individual ministers it would not be appropriate “to advocate for specific options or opine on the likely outcome of the process”.

In a letter to his Cabinet, Mr Burnham said any “fundamental change” to post-Brexit arrangements would be “for the public to decide” and left to the next parliament.

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