SAO PAULO/RIO DE JANEIRO, Aug 8 (Reuters) - Brazilian state-run oil giant Petrobras on Thursday posted a net loss of 2.6 billion reais ($470 million) for the second quarter of 2024, the firm said as it announced lower-than-expected results and a reduction in investment estimates.

Despite the results, the firm's board approved a 13.57 billion-real ($2.45 billion) payout to shareholders in dividends and interest on equity, equivalent to 1.05 reais per share.

The payout will be made using 6.4 billion reais from funds from 2023 extraordinary dividends withheld by the board in March, Petrobras said in a securities filing, leaving the fund with around 15.5 billion reais.

The net loss - the firm's first since the third quarter of 2020 - was a result of a one-off 11.9 billion tax charge and the devaluation of the real, among other non-recurring items, said the firm.

Its net recurring profit fell 46.5% in the period to 15.7 billion reais, below analysts' expectations of 22.3 billion reais, according to LSEG data.

Adjusted earnings before interest, taxes, depreciation and amortization (EBITDA) fell 12.3% in the period, to 49.7 billion reais, below LSEG poll of 63.3 billion reais.

Petrobras also lowered its planned investments for this year to between $13.5 billion and $14.5 billion, from a planned $18.5 billion for 2024.

Its new forecasts include an estimated $11.1 billion to $12.1 billion earmarked for the exploration and production segment. The fresh forecast will not impact its oil and gas production curve, the firm said.

($1 = 5.5473 reais) (Reporting by Fabio Teixeira and Marta Nogueira in Rio de Janeiro and Luana Maria Benedito in Sao Paulo; additional reporting by Andre Romani in Sao Paulo; Editing by Kylie Madry and Stephen Coates)