Brexit must not happen because it will cause incalculable political and economic damage, according to former prime minister Tony Blair.

Blair, a committed Christian who since leaving office has advocated for faith around the world, says in an interview with Sky News to be broadcast tomorrow that it is has insisted it is 'absolutely necessary' that Brexit does not happen.

He says the vote to leave the EU is already causing terrible damage across the UK.

A prominent remain campaigner, Blair believes public opinion is moving away from Brexit.

Theresa May has already triggered Article 50, starting the formal process to exit the EU in 2019.

But in spite of this, Blair says: 'I think it's possible now that Brexit doesn't happen.

'I think it's absolutely necessary that it doesn't happen because I think every day is bringing us fresh evidence that it's doing us damage economically, certainly doing us damage politically.'

In evidence, he cites the fact that this time last year, Britain was the fastest growing economy in the G7.

It is now the slowest.

'Our savings ratio is at the lowest for 50 years, the investment community internationally has now gone really negative on us, our currency's down 10-12 per cent, investment in the motor car industry, for example, is down 30 per cent, living standards are stagnating.

'This is causing us real damage, that's beyond doubt.'

The full interview by Sophy Ridge with Tony Blair will be broadcast Sunday 16 July at 10am BST.