SAO PAULO, Aug 22 (Reuters) - Private equity firm IG4

Capital and banks holding shares in petrochemical Braskem ( BAK )

as collateral for Novonor's debt signed an agreement

for exclusivity in talks for 90 days, Valor Economico reported

on Friday.

The report comes after a 90-day exclusivity period for

Novonor, formerly Odebrecht, to sell a controlling stake in

Braskem ( BAK ) to Brazilian businessman Nelson Tanure expired without a

deal.

Reuters reported, citing sources, that IG4 was working to

launch a rival bid to purchase the controlling stake in Braskem ( BAK ),

as it aims to consolidate Novonor's bank debt and exchange it

for Braskem ( BAK ) shares.