Labour leader Jeremy Corbyn has said he would like to see a cap on the maximum amount people can earn.
He told BBC Radio 4’s Today programme he was "not wedded" to a particular limit but the idea should be looked at.
The UK’s levels of income disparity were getting worse, he said, suggesting this cannot go on "if we want to live in a more egalitarian society".
He also told the BBC he had not changed his mind on immigration and still believed numbers were not too high.
His remarks on immigration, in an interview with BBC political editor Laura Kuenssberg, came ahead of a speech which pre-briefing had suggested would see the Labour leader going cool on the principle of EU freedom of movement.
The idea of a maximum earnings cap was first raised by Mr Corbyn during Labour’s 2015 leadership contest.
He told Today that he now wanted Labour to consider the idea, as levels of income disparity were getting worse.
"We cannot set ourselves as being a sort of grossly unequal bargain basement economy on the shores of Europe. If we want to live in a more egalitarian society and fund our public services, we cannot go on creating worse levels of inequality," he said.
How would national maximum wage work?
Analysis by Kamal Ahmed, BBC business editor
Given that a direct limit (making it "illegal" for example for anyone to earn over, say, £200,000) would be almost impossible to enforce in a global economy where income takes many forms – salary, investments, returns on assets – very high marginal rates of tax could be one way to control very high levels of pay.
Another could be by imposing limits on the pay ratio between higher and lower earners in a company – possibly a more politically palatable option.
The High Pay Centre, for example, supports considering this approach.
Speaking later on Sky News, Mr Corbyn said a wage cap would be "somewhat higher" than his salary of approximately £138,000, adding that the salaries some footballers receive were "simply ridiculous".
In an interview with the BBC’s political editor Laura Kuenssberg, he said it was indefensible for chief executives of some of the UK’s largest companies to be earning 100 times what their employees were taking home.
"Either you do a cap or you look at the levels of disparity within organisations," he said. "Other countries have got some policies developing this and I think we need to consult with them and learn some lessons on this."
Labour has also said it will introduce a "real living wage" of at least £10 an hour if in power.
The BBC’s assistant political editor Norman Smith said an ally of Mr Corbyn’s on the shadow cabinet said they knew nothing about the maximum wage policy. And the idea received a lukewarm response from some Labour MPs.
Emma Reynolds told the BBC’s Victoria Derbyshire show that she would need to see the details but "instinctively" she believed there were "other ways" to tackle the pressing issue of income inequality, with a focus on "what you own as well as what you earn".
And John Woodcock – a critic of Mr Corbyn – tweeted: "Government on ropes over massive pressure on A&E departments. Let’s keep the focus on that rather than alternatives presented this morning."
UKIP leader Paul Nuttall said a cap on earnings would amount to the "politics of envy" and would see the "best people" in the City moving abroad.
Before becoming prime minister, Theresa May suggested shareholders hold binding votes on executive pay and publish the pay differentials between executives and workers. She has since been accused of watering down planned changes following business criticism.
Edwin Morgan, from the Institute of Directors, said a pay cap was a "blunt tool" and it was "not feasible" for politicians to determine fair levels of pay. But he said top firms needed to listen to public and political concerns and "moderate" their pay awards.
In his Today interview, which came ahead of a speech on Brexit later on Tuesday, Mr Corbyn also said he would be prepared to join striking Southern Rail workers on the picket line in their long-running dispute over the role of guards.
On Europe, Mr Corbyn attacked the government’s lack of clarity over its negotiating objectives and said while there was no doubt that Brexit would happen, the UK must continue to have a close trading relationship with the EU after its exit.
"What we don’t want to do is turn Britain into a bargain basement economy on the shores of Europe where we continuously reduce corporation taxation, encourage a low-wage economy," he said. "Instead what we want is a high-value economy with skilled jobs promoting high-quality exports."
According to excerpts of his speech, Mr Corbyn will say later that he is "not wedded" to the continued free movement of people as a matter of principle.
Asked what this meant in practice, he said: "We are not saying that anyone could not come here because there would be the right of travel and so on. The right to work would have to be something that would have to be negotiated. That cannot clearly be put down yet until we know what the terms are of the single market access point."
In his interview with BBC political editor Laura Kuenssberg he said that he did not think immigration was too high, but he claimed measures to end "exploitation" of foreign workers under EU employment laws would "probably" bring down numbers.
EU leaders have said that curbs on free movement are incompatible with continued membership of the single market.