June 28 (Reuters) - Brazilian state-run oil giant Petrobras ended its tolling agreement with chemical company Unigel, Petrobras said on Friday in a statement.

According to Petrobras, the contract ended because it did not meet efficiency conditions within its deadline, which fell on Thursday.

The decision comes after Brazil's federal audit court (TCU) said it found irregularities in Petrobras' contract with Unigel during a preliminary review by its technical staff earlier this year.

At the time, TCU estimated Petrobras could lose a total of 487 million reais ($87.1 million) in the eight months covered by the arrangement.

Under the deal, signed in late 2023, the oil company had agreed to supply natural gas for Unigel to produce nitrogen fertilizers at two plants it leased from Petrobras in the states of Bahia and Sergipe.

The contract was terminated before it took effect, said Petrobras. The firm said it is still in talks with Unigel to find a solution to provide fertilizers to the Brazilian market. (Reporting by Luana Maria Benedito and Fabio Teixeira; Editing by Leslie Adler and Chris Reese)