(Adds Transpetro comment)
RIO DE JANEIRO/SAO PAULO, Nov 21 (Reuters) - Brazilian police detained six people as part of an investigation into suspected bribery at a unit of state oil company Petroleo Brasileiro SA, prosecutors said on Tuesday, in the latest phase of Brazil's sprawling 'Car Wash' corruption probe.
Police carried out eight search warrants related to the scheme at Petrobras, as the company is known. Prosecutors said illegal payments were made by a contractor to a former manager of Transpetro, a subsidiary of Petrobras.
"Transpetro is examining the accusations of irregularities in the company's contracting process," the company said in a statement. "Transpetro reiterates that it is the victim in these cases and it lends all support necessary to the Car Wash investigation."
Prosecutors said the payments to the unnamed manager totaled 7 million reais ($2.2 million) between 2009 and 2014. According to investigators, part of those bribes were then passed to Brazil's leftist Workers' Party.
The latest graft allegations, while small in comparison to the rest of the Car Wash probe, underscore the challenge to Petrobras of putting a multi-year corruption scandal behind it.
The investigation unveiled on Tuesday follows revelations of a separate alleged scheme involving Transpetro and President Michel Temer's Brazilian Democracy Movement Party (PMDB).
In September, a Brazilian prosecutor charged six current and former PMDB senators of unduly receiving 864 million reais in bribes, generating losses of 5.5 billion reais at Petrobras and 113 million reais at the Transpetro subsidiary.
As part of the most recent investigation, police said the arrests are taking place in the states of Sao Paulo, Santa Catarina, Sergipe and Bahia.
$1 = 3.26 reais Reporting by Pedro Fonseca and Gram Slattery; writing by Gram Slattery; Editing by Matthew Mpoke Bigg and Andrew Hay