Retailer Sports Direct has dismissed criticism by Ed Miliband of its use of zero-hours contracts.
The Labour leader called it a "terrible place to work" and pledged to ban "the exploitation" of such contracts.
Labour claims 17,000 of Sports Direct's 20,000 UK staff are not guaranteed regular hours.
In response the company said it was reviewing "core" employment procedures, but a spokesman added: "With enemies like these, who needs friends?"
BBC political correspondent Alan Soady said this comment was meant as mockery of Mr Miliband, following recent reports that some Labour figures want him to step down amid poor poll ratings.
Sports Direct also reiterated a statement it had already made, saying: "The company will continue the process of reviewing, updating and improving our core employment documents and procedures across our entire business beyond its existing compliant framework."
Zero-hours contracts do not guarantee regular work, and sick pay is often not included.
Speaking to the West Midlands Labour Party conference in Coventry, Mr Miliband attacked what he called "a zero-zero economy - of zero-hours contracts and zero tax for those at the top".
Mr Miliband pledged that, under a Labour government, "if you work regular hours you will have a legal right to a regular contract".
He said Sports Direct "has predictable turnover, it has big profits but, for too many of its employees, it is a terrible place to work".
"We cannot go on with an economy that allows businesses to use zero-hours contracts as the standard way of employing people month after month, year after year," he said.
"These Victorian practices have no place in the 21st Century."
Business and Enterprise Minister Matthew Hancock said: "We're already tackling the abuse of zero-hours contracts - after 13 years of Labour doing absolutely nothing about it."