Downing Street said today that Theresa May would never agree to a permanent customs union with the EU, as the Prime Minister attempts to set cabinet ministers at ease over the Brexit negotiations.
“The Prime Minister would never agree to a deal which would trap the UK in a backstop permanently,” a spokeswoman told the BBC.
Ministers reportedly feared the Prime Minister could consent to such an arrangement if the UK fails to reach a trade agreement by May's deadline of March 2019.
EU leaders will meet next week to discuss the terms of the Brexit deal. If the talks go positively, then they will organise a special summit in November to conclude an agreement.
The DUP, which assists Theresa May's Conservative government in key Commons votes, has warned it could vote against her Budget next month if Brexit discussions between the UK and the EU result in trade barriers between the isle of Great Britain and Northern Ireland.
The future of the border between Northern Ireland and Ireland has proved to be a key issue in the Brexit talks.
Brussels has suggested that in the event of no deal, Northern Ireland should stay in the EU customs union - something the UK has repeatedly rejected as it would create a new border between Northern Ireland and the UK across the Irish sea.
Amid fears over the direction of the talks, it has also emerged that the M26 in Kent is being closed overnight as part of contingency plans to to see if it can be used as a car park for lorries in the event of no Brexit deal being reached between the UK and the other 27 EU nations by March 2019.
The road is 10 miles long, and connects the M25 at Sevenoaks and the M20 near West Malling. It will be closed from 10pm until 5.30am until 15 October and then again at various intervals between 19 November and 21 December.