Two UK organisations representing thousands of businesses have attacked Labour for a pledge to “politicise the Low Pay Commission” and raise the minimum wage in arbitrary increments.

In a speech at the Labour conference today, the shadow chancellor Ed Balls said he would increase the minimum wage, increase the top rate of income tax and introduce a mansion tax on properties worth more than £2 million if Labour wins the next election.

Earlier, Labour leader Ed Miliband said he would raise the minimum wage to £8 per hour for adults by 2020, forcing increases year-on-year and removing rate-setting powers from the Low Pay Commission.

The Federation of Small Businesses described the pledge as a “huge risk”. The group’s chair, Mike Cherry, told the Financial Times newspaper: “If it goes up to £8 over that period there is always a danger that it will cost jobs.

“No one can forecast what the economy will do over the next three to five years. The important thing is that I don’t want the Low Pay Commission, which is incredibly sensible in setting credible rates, to be politicised – that is my biggest concern over this sort of statement.”

Meanwhile, the CBI, which represents many of the country’s biggest businesses, said setting the minimum wage should be left to independent experts and should not be “politicised”.

CBI director general John Cridland said: Setting the minimum wage should be left to the independent experts at the Low Pay Commission. Attempting to fix future levels now is finger-in-the-air economics which takes no account of the economic realities at that time, nor the ability of firms to pay.

He added: "Instead, politicians should address how people move on in their careers, through training and better skills, helping them move to higher paying roles over time."

In his speech today, Mr Balls promised a cut in business rates, a freeze in energy pricing, scrapping of the bedroom tax and extending by one year the one per cent cap on child benefits.

Pledges welcomed by the CBI included addressing the UK deficit, recognition of the importance of the single European market, more housing construction and a tacit backing of an extension for Heathrow airport.