OPEC's decision could cause gasoline prices to rise in Brazil.

By Rodrigo Viga Gaier

RIO DE JANEIRO (Reuters) - Petrobras will monitor the effects of the Organization of the Petroleum Exporting Countries' (OPEC) decision to reduce production on commodity prices in the coming days to determine the prices of refined products at the state-owned company's refineries, but the trend is upward, a source close to the discussions told Reuters on Wednesday.

The current exchange rate also creates an upward bias for Petrobras' fuel prices, the source added, speaking on condition of anonymity.

"Certainly, the bias today is much more towards an upward bias than a downward one. Without a doubt," he said.

OPEC countries produce about a third of the world's oil, or about 33,6 million barrels per day, and under Wednesday's agreement they are expected to reduce production by about 1,2 million barrels per day starting in January 2017.

The dollar is about 7 percent stronger against the real, and Brent crude oil is approximately 8,5 percent more expensive compared to November 8, when the state-owned company made the decision to reduce prices.

Higher oil prices and a stronger dollar would, in theory, lead Petrobras to raise its prices, but there are other variables considered in the company's new policy, which provides for evaluations at least once a month.

"The company won't make a decision immediately. It takes a couple of days to see if there's a significant change or not. Any change, if made, would take effect next week," the source said.

Brent crude oil closed up 8,8 percent on Wednesday.

Following the gains in oil prices, Petrobras' preferred shares rose by about 9 percent.

Since announcing its new pricing policy and the creation of a committee to deal with refined products in October, the oil company has already reduced the price of diesel and gasoline twice, at a time when it was losing market share to imported products.

Analysts point to an increase.

Analysts consulted by Reuters assessed on Wednesday that the rise in oil prices, following an OPEC agreement to cut production, and in the dollar, in the wake of Donald Trump's election in the United States, should be strong arguments for Petrobras to raise gasoline and diesel prices in Brazil.

When contacted, Petrobras merely reaffirmed some guidelines of its pricing policy.

The company stated that it takes the following factors into account when setting prices: international parity price (PPI), which already includes costs such as shipping costs, internal transportation costs, and port fees; a margin to compensate for the risks inherent in the operation, such as exchange rate and price volatility, port demurrage, and profit, in addition to taxes; market share level; and prices never below international parity.

(With additional reporting by Gustavo Bonato)