The move underscores how buyout firms, long associated with saddling companies with debt and slashing costs and jobs, are now seeking to offer products to investors that also appeal to an environmental, social and governance (ESG) business agenda.

KKR's new unit will seek investments in smaller medium-sized companies focussing on areas such as renewable energy, education and environmental management, according to one of the sources, who spoke on condition of anonymity as the information is not public.

KKR's approach will be to make private equity-style investments in these companies, with the aim of building up businesses and earning a profit from a future sale comparable to traditional buyout fund returns, the sources said.

The new fund, which has investment themes tied to the United Nations' Sustainable Development Goals, does not have an identified size, but is currently engaging with potential investors about contributing to it, three of the sources said.

The business will be run by Robert Antablin, previously KKR's head of energy private equity for the Americas, and Ken Mehlman, KKR's global head of public affairs, the sources said.

Antablin will move to New York from Houston under the new role, one of the sources said. His responsibility for energy private equity investments had moved earlier this year to David Rockecharlie, the firm's head of energy real assets, another of the sources added.

A spokeswoman for KKR, whose assets under management totalled $168 billion at the end of 2017, declined to comment.

Other private equity firms are beginning to launch similar offerings focussed on investors' social responsibility agenda. TPG Capital's $2 billion (£1.44 billion) Rise Fund, for example, invests in five areas including agriculture and education, and counts musician and activist Bono as a founding stakeholder.

KKR has made investments in the past that fit into the profile of companies its new fund would target, such as China Modern Dairy Holdings, which sells higher-end dairy to the country's growing middle class when milk standards have been questioned.

(Reporting by David French and Joshua Franklin in New York; editing by G Crosse)

By David French and Joshua Franklin