Brazilian state-owned Petrobras said a two-month deal to supply naphtha to petrochemicals producer Braskem was being extended while the two companies work on a long-term agreement.
The current deal expires Saturday.
Petrobras and Braskem have been in talks for months on a deal that will secure naphtha supplies for Latin America's largest petrochemicals producer.
The talks have been tricky after the two companies uncovered irregularities in a previous supply deal signed in 2009.
Executives at construction and engineering firm Odebrecht, which is Braskem's controlling shareholder, have been accused by local prosecutors of paying bribes to secure naphtha at below-market prices.
Braskem and Odebrecht have denied any wrongdoing.
But Petrobras has been scrutinizing contracts involving companies named in an ongoing corruption investigation, as it beefs up corporate governance and transparency.
Many of the companies have been barred from signing new contracts with Petrobras, although existing deals have been honored.
Odebrecht owns a 38.3% stake in Braskem, but controls the company with 50.1% of the voting shares. Petrobras holds a 36.1% stake and 47.0% of the voting shares.
