Brazilian state-controlled oil company Petróleo Brasileiro SA could take a charge of about 52 billion reais ($20 billion) in its delayed third-quarter results to reduce the value of some assets, a Veja magazine blog said on Monday.

The impairment equals 42 percent of the market value of Petrobras (PETR4.SA), as the company is known, Veja's Mercados blog said, citing sources close to the company. A Petrobras spokeswoman declined to comment on the report but reiterated the company's plan to release third-quarter results on Tuesday.

On Friday, O Globo newspaper reported that a 10 billion real write-off and a 30 percent cut in capital spending this year were under consideration to help Petrobras preserve cash amid the impact of a contract-fixing, bribery and political kickback scandal. Petrobras faces limited access to financial markets as a result of the scandal and falling oil prices. 

Petrobras pledged to invest about $44 billion a year under a five-year, $221 billion investment plan announced last year, but it warned in December that it would cut spending.

Veja's Mercados blog did not specify which areas would be targeted in the write-off. The blog also said Petrobras hired Deloitte Consulting LLP to help decide the "size and scope" of planned impairments.

Third-quarter results, originally scheduled for release in November, were delayed after a probe of corruption at Petrobras led auditor PricewaterhouseCoopers to refuse to certify the company's accounts.

Reuters reported on Jan. 6 that Petrobras' third-quarter results were likely to reflect the full amount of write-downs from the scandal.

Police, prosecutors and suspects arrested in the case said Petrobras executives conspired with construction and engineering companies to inflate the value of contracts for refineries, ships and other goods and services.

They said some of the excess charges were then kicked back to executives, politicians and political parties as bribes and campaign contributions. About 40 people have been arrested in the case, including three former Petrobras senior executives and senior executives of some of Brazil's largest construction and engineering companies.