RIO DE JANEIRO, July 24 (Reuters) - Brazilian oil workers began a 24-hour strike on Friday in an effort to stop moves to shrink state-run oil company Petroleo Brasileiro SA, or Petrobras, according to the main union representing the workers.
The strike, led by FUP, the country's largest federation of oil workers called for refinery, oil platform and other employees to walk off their jobs at Petrobras at midnight Thursday (0300 GMT Friday).
The union is fighting plans by Petrobras to sell $15.1 billion of assets by the end of 2016.
Petrobras wants to pay down debt - which at about $120 billion is the most held by any oil company - as well as generate cash for investment and revive investor confidence after a giant corruption scandal.
FUP also opposes a bill before Brazil's Senate seeking to strip Petrobras of its right to run all new development work in a giant offshore area known as the Subsalt Polygon. The bill would also end a requirement that Petrobras take a minimum 30 percent stake in exploration and production rights in the area.
FUP opposes any non-government involvement in Petrobras and wants the company, which has had non-state shareholders since the 1950s, totally nationalized.
While most Petrobras strikes have had little or no impact on production, FUP is looking to replicate the results of a 31-day strike in 1995. That strike ended due to the government threatening mass layoffs, but union leaders say it helped avert a privatization of Petrobras in 1997, although the company was still stripped of its monopoly on exploration, production and refining in Brazil.
Under Brazilian law, unions must cooperate in the safe operation or shutdown of dangerous facilities. As a result, the 24-hour strike will leave many union members on the job.
Petrobras officials have said that it takes about five to 10 days after the start of a strike for a walkout to have a significant impact on oil or fuel output.
While Petrobras remains controlled by the state, most of its shares are owned by non-government investors. It is one of the largest non-U.S. companies on the New York Stock Exchange.
"The company should not be used to guarantee the profits of investors," FUP said in a statement on Thursday. "It should be a spring to drive social and economic development in Brazil."
Petrobras officials did not respond to requests for comment. (Reporting by Jeb Blount; Editing by Dan Grebler and Tom Hogue)