North-east Scotland and Kent are the UK regions poised to bear the biggest economic brunt of a no-deal Brexit, a leading economic forecaster has said.

Regional estimates produced by the National Institute for Economic and Social Research (Niesr) said the Scottish region’s dependence on the local oil industry and its trade with Europe meant a hard Brexit could knock growth by 6.3pc compared to continued EU membership.

Niesr added that Kent was the second most potentially exposed region with a 5.8pc fall in output due to its geographical proximity to Europe and its concentration of exporters and importers.

The estimates come as Operation Yellowhammer documents published by the Government this week showed Kent particularly exposed to a hard Brexit.

The contingency plans say disruption to the Dover-Calais traffic flow could lead to “significant queues in Kent” and maximum delays of up to two and a half days in a “reasonable worst case scenario”.

The head of the Port of Calais, Jean-Marc Puissesseau, labelled the fears of disruption and miles of tailbacks as “catastrophism” in the summer.