SAO PAULO, Aug 29 (Reuters) - Brazil's state-run oil

firm Petrobras has been receptive to a proposal by IG4 Capital

to take over engineering group Novonor's controlling stake in

Latin America's largest petrochemical company, Braskem ( BAK )

, four people familiar with the talks told Reuters.

Petrobras, Braskem's ( BAK ) second-largest shareholder, holds a

right of first refusal for Novonor's stake under a shareholder

agreement, so its approval is vital for the deal to go ahead.

Two of those sources and three others, speaking on condition

of anonymity, said IG4's conversations with key stakeholders

have made progress since the firm last week signed exclusive

rights to acquire billions of reais of Novonor debt from

Brazil's largest banks, including state development bank BNDES.

The accord gave private equity firm IG4 the sole right to

negotiate with Novonor and Petrobras to then swap that debt for

Braskem ( BAK ) shares, sources said.

Three sources said the deal could be finalized within a few

months if talks continue at the current pace, leading to a

complete overhaul of Braskem's ( BAK ) management, although they

emphasized the uncertainty about any timeline for negotiations.

A new controlling shareholder - and a potential injection of

fresh capital - could breathe new life into Braskem ( BAK ), which has

struggled with tight margins in the petrochemical business and

lingering liabilities from neighborhoods damaged by its salt

mining operations under the northeastern city of Maceio.

Brazilian President Luiz Inacio Lula da Silva has made clear

to ministers that he wants to see Braskem ( BAK ) in good health and

asked Petrobras CEO Magda Chambriard to help find a solution

that does not compromise the oil firm's interests, according to

two people close to the presidential palace.

The presidential press office did not immediately respond to

a request for comment. IG4, Novonor, Petrobras and Braskem ( BAK )

declined to comment.

Reuters first reported in November that Brazil's government

and major commercial banks were working on a plan to transfer

Novonor's Braskem ( BAK ) stake to a private equity fund.

The deal could resolve the outstanding debt hanging over

Novonor, formerly known as Odebrecht, which ballooned during the

Car Wash corruption scandal about a decade ago, when the group

pledged its Braskem ( BAK ) shares as collateral for 15 billion reais

($2.8 billion) in bank loans.

The debt has since grown to close to 20 billion reais - more

than twice Braskem's ( BAK ) current market value.

Novonor has explored selling its controlling interest in

Braskem ( BAK ) for years, but has failed repeatedly to clinch a deal,

including in recent negotiations with Brazilian businessman

Nelson Tanure, whose period for exclusive talks with Novonor

expired last week.

Two people close to Petrobras confirmed discussions with IG4

are underway, but one of them added that a deal with Tanure has

not been completely ruled out. Both sources said Petrobras is

aiming for more influence in Braskem's ( BAK ) management once Novonor

relinquishes control.

One of the sources said Novonor is open to "building a

solution", as long as all parties involved end up gaining.

Novonor may also want to retain a small stake in Braskem ( BAK ), as the

revenue coming from the company helps meet its obligations under

the judicial recovery plan, the person added.

Novonor currently holds 50.1% of Braskem's ( BAK ) voting shares and

38.3% of total shares. Petrobras owns 47.0% of voting shares and

36.1% of total shares.

($1 = 5.42 reais)