RIO DE JANEIRO, Feb 26 (Reuters) - Brazil's Petrobras

posted a net loss of 17 billion reais ($2.8 billion)

in its fourth quarter due to exchange rate variation on debts

between the state-run oil firm and its subsidiaries abroad, it

said in a filing on Wednesday.

According to Petrobras, the financial transactions did not

impact its cash flow, and excluding them, the firm would have

posted a net profit of 17.7 billion reais in the quarter.