Labour leader Jeremy Corbyn has launched an attack on "big business" in his speech to delegates at the party's conference in Brighton.
He has pledged to nationalise the utilities sector to stop the public being "ripped off", reiterating promises made by his shadow Chancellor John McDonnell earlier this week.
"We are going to ask big businesses to pay more tax," he said.
Corbyn said there would be a new and widespread role for the public sector "particularly where the private sector has failed."
He also said he would crack down on developers holding onto land. "As Ed Miliband said, use it or lose it," Corbyn said.
Business groups have reacted strongly against the economic agenda set out by the Labour party this week, warning that Corbyn's plan to seize whole industries into public ownership would send investors running.
While lobby groups have said they will sit down and work with McDonnell's team, City A.M. understands that many business bosses are worried that some in the Labour camp simply do not understand the full implications of their proposals.
"There is a rising concern amongst businesses about the two largest parties in Westminster, with one flirting with fantasy economics while the other engages in an unedifying playground bust-up,"said Adam Marshall, director general of the British Chambers of Commerce.
"Businesses of all sizes want to see pragmatism, realism and economic competence across the political spectrum at such a critical moment for the United Kingdom."