(Adds estimated strike-related oil output cuts, union comment)
By Jeb Blount and Rodrigo Viga Gaier
RIO DE JANEIRO, Nov 4 (Reuters) - Petrobras oil output in Brazil is holding steady at about 179,000 barrels a day below levels recorded before workers began a strike against the state-owned oil company on Sunday, a company source told Reuters on Wednesday.
Production of oil is about 8.5 percent below pre-strike levels of about 2.1 million barrels a day, based on production estimates released by Petrobras since the strike began.
Output levels on Tuesday and Wednesday are higher than they were on Monday, when Petrobras said the strike by unionized workers was costing it about 273,000 barrels a day of output, or 13 below pre-strike levels, the source said.
The cuts have already caused the biggest strike-induced hit to Petrobras' output since a 32-day strike in 1995 that led to lines at gas stations and military occupation of refineries. The latest strike is also likely to increase pressure on a company hobbled by a corruption scandal and debt of $130 billion, the largest in the world oil industry.
The company source said that the strike is having a "significant" financial impact on the company. The source asked for anonymity because no authorization had been given to talk to the press.
While the walkout is spreading, Brazilian strikers, by law, face some limits on how much production they can stop and how quickly they can stop it. Unions are required to make sure their decision to lay down tools at refineries, oil platforms and other dangerous installations is carried out safely.
Management can try to run refineries or oil platforms on its own if it is able to do so with contingency measures.
Production from the giant Roncador offshore oil field in Brazil's Campos Basin, for instance, continued on Wednesday after workers on the field's production vessels joined a four-day strike, an oil workers' spokesman said, denying media reports of an output shutdown.
Tezeu Bezerra, head of communications at Sindipetro Norte Fluminense, which represents workers on Roncador platforms, said the strike did not stop output at the P-52, P-54, P-55, and P-62 floating production vessels which were operating under management contingency plans.
"There is nothing that we'd like more than to say that Roncador is stopped," he said. "But that's not true, the workers have joined the strike but production continues."
Bloomberg News, citing sources it did not identify, reported earlier that production of Roncador crude had been halted on those platforms after workers joined the strike. (Additional reporting by Marta Nogueira; editing by Grant McCool)