Labour's Brexit plans have descended into chaos after Sir Keir Starmer suggested the UK should remain in the Customs Union and try to negotiate a new form of single market membership.

The shadow Brexit secretary said the party is clear that Britain will leave the EU as another referendum is "not viable", but the option of retaining UK membership of the EU Customs Union "should be left on the table".

Both Jeremy Corbyn and John McDonnell, his shadow chancellor, have insisted that the party is formally committed to taking Britain out of the single market and the Customs Union.