US based private equity firm Apollo Global Management (APO) is said to be ahead of its rivals Philip Falcone's Harbinger Group in bidding race to purchase Aviva US life insurance and annuities unit.

Sources familiar with the development were cited by Bloomberg as saying that APO had collaborated with Guggenheim Partners to jointly bid for the unit, which will be sold out at a "substantial discount" to the unit’s book value, excluding debt, of £2.4bn ($3.8bn).

Aviva, the UK based underwater is planning to offload 16 of its businesses, in order to concentrate on core businesses segment as well as to shore up the necessary capital.

Although, the deal is in its infancy stage, it may not progress if the concerned parties could not fulfill mutual expectations.

The US insurer employees 36,600 staffs and serves approximately 43 million customers across the globe.