SAO PAULO, Aug 11 (Reuters) - Brazilian businessman

Nelson Tanure may give up on his bid to acquire a controlling

stake in Latin America's largest petrochemical firm Braskem ( BAK )

as his exclusive negotiations window nears closing

without an agreement to resolve claims from an environmental

incident linked to the company.

Last May, Tanure signed a 90-day exclusivity document to

discuss the terms of an offer to acquire a controlling stake in

Braskem ( BAK ) from Novonor, formerly Odebrecht. The businessman has

since been working to resolve issues stemming from environmental

investigation into ground subsidence in the northeastern city of

Maceió, where Braskem ( BAK ) had rock salt mines.

In a written response to Reuters on Monday, Tanure said

settling this case is a non-negotiable term for his Braskem ( BAK ) bid,

whose current exclusivity period ends on August 21.

"An agreement with all entities involved in the Alagoas

disaster is a sine qua non (condition), and especially applies

to the non-transfer of criminal and financial responsibility to

the new shareholders," he answered without elaborating on his

next steps.

The incident was allegedly caused by Braskem's ( BAK ) rock salt

extraction activities, which began in the 1970s and were halted

in 2019 after authorities determined they contributed to the

sinking of five neighborhoods, leading to the displacement of

thousands of residents.

As Tanure mulls his next moves, private equity firm IG4

Capital is biding its time, poised to launch a rival bid when

Tanure-Novonor agreement lapses. IG4's strategy aims to

consolidate Novonor's bank debt and exchange it for Braskem ( BAK )

shares, sources said.

Braskem ( BAK ), Novonor and IG4 all declined to comment .

The critical decision period coincides with Brazil's

Unipar's reported attempt to purchase Braskem's ( BAK ) U.S.

polypropylene plants for about $1 billion. Made public last

week, the bid lacks approval from key parties, including Tanure

and IG4, according to sources.