Lehman Brothers Holdings Inc. -- currently under bankruptcy court protection -- has reached a deal to sell its private equity unit and spin it off into an independent firm, according to reports.

In the deal the unit would also take investment from South Arican billionaire Johann Rupert, according to the anonymous source. Lehman's bankruptcy estate will retain substantial interest in the funds, the source added.

The business known as Lehman Brothers Merchant Banking manages about $4.5 billion through two funds and holds stakes in more than a dozen mainly midsize companies.

The deal reveals the decision of Lehman Brothers' advisers Alvarez & Marsal, to keep and manage Lehman assets and not sell them into the worsening market.

Lehman filed for the U.S. largest bankruptcy protection four months ago.