Jeremy Corbyn has called for a cap on pay for the UK's highest earners in order to create a more "equal society."
The Labour leader said action was needed to counter the growing levels of income disparity in Britain.
He said he did not want to see the UK become a "bargain-basement economy" on the fringes of Europe in the wake of the vote to leave the EU.
"We have worse levels of income disparity than most of the OECD countries in this country. It is getting worse," he told the BBC Radio 4 Today programme.
"If we want to live in a more egalitarian society and fund our public services, we cannot go on creating worse levels of inequality.
"I would to like to see a maximum earnings limit, quite honestly, because I think that would be a fairer thing to do.
In a later television interview, Corbyn explained the pay cap would be "somewhat higher" than the £138,000 he earns as an MP and as Leader of the Opposition.
He told Sky News: "I think it would be somewhat higher than that. I am not going to put a figure on it.
"What I am going to say is that we are looking at this issue of the disparity of pay within big companies and organisations and do something to try and close that gap."
Corbyn has also criticised employers in Britain who were "under-cutting" working conditions by employing cheap migrant labour.
Speaking to ITV's Good Morning Britain, he said if employers played fair then the number of people coming to the UK from Europe would likely decrease.
But when asked if he would back continued free movement as the price of access to the single market, the Labour leader said: "If the EU, as is, says access to the single market requires the continuation of free movement, then there's a choice to be made."
The Islington North MP is expected to say Britain could be "better off" outside the EU in a speech later today.