The EU's free movement rules have made British businesses lazy, according to Iain Duncan Smith. The former work and pensions secretary told IBTimes UK access to low-skilled workers from the single-market has meant some firms have failed to invest in their workforce.
Smith also said he expected the government to introduce border controls as part of the UK's split from the EU.
The move would mean Britain would no longer have access to the single-market, with the likes of European Parliament President Martin Schulz and European Council President Donald Tusk ruling out "single market a la carte".
"You don't have hard borders, you have access to work controls," Duncan Smith said. "So people can't just come in without a job and they can't come in and claim benefits.
"Most of the EU influx is in low-skilled work, 80%, and that's where it's done all the damage to people's salaries and incomes at the bottom. It's also made British business rather lazy, just going out and hiring somebody from somewhere and not training them up. So there's going to be a cultural shift for business, they are going to have to apply for work permits."
But the senior Conservative MP said high-skilled workers, such as academics, will face a "light tough" work-permit system, which "basically means they will be able to come and go much as they please".
The comments echo the remarks of fellow Leave campaigner and International Trade Secretary Liam Fox, who claimed UK businesses were becoming "too fat and too lazy".
"This country is not the free-trading nation it once was. We have become too lazy, and too fat on our successes in previous generations," Fox told a Conservative Way Forward event, according to The Times.
Theresa May, meanwhile, has revealed that her government will trigger Article 50 of the Lisbon Treaty, the official mechanism to begin the process of extricating the country from the EU, before the end of March 2017.
The prime minister and Brexit Secretary David Davis will announce their plans for a Great Repeal Bill at the Tory conference in Birmingham later today (2 October).
The proposed legislation will enshrine all EU law in UK statutes, while the government plans to scrap the 1972 European Communities Act (ECA). Duncan Smith welcomed the news.
"I'm very pleased about it, we recommended [the prime minister] gets on with it. It gives a sense of momentum in parliament and allows people to debate various issues, while stopping people feeling like nothing has happened."