A Labour government would slash business rates for 1.5 million small firms in the UK in a bid to make the tax system "fairer" for companies, Ed Balls will announce.

The shadow chancellor is expected to make the general election manifesto pledge when he visits Swindon with fellow Labour front bencher Chuka Umunna.

Balls will claim that the business rates move would "unleash the potential" of smaller firms to grow, create more jobs and raise living standards.

He will explain that the move will be paid for by reversing the government's 1% cut to corporation tax to 20% from April.

"Under the Tories higher business rates have cost firms an average of £1,500 ($2,217) a year and are an ever bigger part of their tax burden," the shadow chancellor will say.

"So instead of another corporation tax cut for large companies which helps fewer than one in 10 firms, we will cut and then freeze business rates for small firms instead.

"This is the right priority when money is tight. And it will mean that the tax burden on small businesses will be lower with Labour than under the Tories."

Balls will add: "Every large business started off as a small business and I want to ensure smaller firms have the support they need to grow, invest, innovate and raise their productivity.

"Our plan will help small firms create more high skilled, high paid jobs which are vital to raising living standards."

Tory Treasury minister David Gauke said Labour's plan could cost almost 100,000 jobs and put "people's economic security at risk".

"This would be the first time corporation tax has risen in over 40 years and Labour's plans could cost 96,400 jobs - it would put people's economic security at risk," Gauke said.

"The Conservative Party is helping businesses small and large as part of our long-term economic plan - we don't divide them up for the sake of making a political point.

"By cutting taxes on jobs and investing in infrastructure there are 760,000 more businesses in our country with 1.9 million more people in work than in 2010."

The pledge will be announced during the first day of the general election campaign after David Cameron asked the Queen to dissolve parliament yesterday.

Elsewhere, the prime minister promised that a Conservative government would create an extra two million jobs and Nick Clegg committed the Liberal Democrats to spending £3.5bn on mental health care in England.

The latest opinion poll from YouGov, which was conducted on 30 March, put Labour and the Tories neck-and-neck (35% vs 35%), with just 37 days to go before polling day on 7 May.