Warren Buffett on Wednesday threw his support behind a proposal to increase tax on private equity and hedge fund managers as part of a broad appeal to US law­makers to address widening income inequality.

The statement by Berkshire Hathaway’s chief executive stood in contrast to a lobbying campaign by business groups to stop legislators in the Senate from adopting a proposal that would more than double the tax rate for executives at buy-out groups such as Carlyle, as well as property partnerships and venture capital firms.