Labour has set aside a £4 million war chest to fight a snap election amid belief a vote will be called before 2020, it can be revealed.

The “fighting fund” has been ring-fenced from other spending in an attempt to make sure the party can go toe-to-toe with the Tories financially.

Senior Labour sources said the cash would be used to fund a nationwide advertising blitz and a digital campaign to engage voters through Facebook and Twitter.

The money may also go towards creating full time jobs in regional Labour parties to get hundreds of thousands of activists knocking doors.