Details of US cosmetics company Coty's acquisition of Proctor & Gamble's (P&G) beauty assets could take at least two weeks to be finalized, sources close to the matter said on Tuesday.

For tax purposes, the transaction is to be completed through a "Reverse Morris Trust," which means that P&G would spin off its beauty assets into a separate company that would then absorb Coty in an all-share deal, the sources said.

Coty won an auction at the weekend valuing the businesses at close to $12 billion, the sources said. If it goes through, it would be the biggest deal in cosmetics in at least a decade and would turn Coty into a world leader in perfume and hair care.