Paul Nuttall, the Ukip leader, will attempt to win back voters abandoning his party on Sunday by pledging a ‘one in, one out’ immigration policy.

The party will adopt a net migration target of zero over a five-year period, meaning the same number of people move to Britain as leave to live abroad.

In practice it would mean cutting the number of migrants moving to the UK from 600,000 a year to around 300,000 a year.

A new Migration Control Commission would be created and told to deliver the target, which the party has framed as “balanced migration”.

The party suffered a humiliating result last week in the local elections as it lost all but one council seat it contested.