RIO DE JANEIRO (Reuters) -Brazil’s federation of oil workers, known as FUP, announced on Thursday a two-day warning strike at state-run oil company Petrobras "in protest against the stagnation in negotiations with the company," according to a statement.

The strike, which still needs final approval by the union members, is set to take place between May 29 and May 30 and comes as the oil giant pledges to take austerity measures to cope with lower oil prices.

Petrobras earlier this week reported a first-quarter net profit of 35.2 billion reais ($6.25 billion), but said that lower Brent crude oil prices would require the firm to cut costs where possible.

"Dissatisfaction increased after statements by Petrobras’ Chief Executive Magda Chambriard signaling expense containment plans, even in the face of the company’s positive financial performance," FUP said in the statement.

The main negotiations between the union and the firm are around Petrobras’ variable compensation plan and the cost-cutting policy, which FUP said was "incoherent".

Petrobras did not immediately respond to a request for comment.

($1 = 5.6275 reais)