SAO PAULO, Sept 2 (Reuters) - Brazilian reinsurer IRB Brasil Resseguros SA confirmed late on Thursday it had raised 1.2 billion reais ($228.9 million) in a share offering, after successive monthly losses led analysts to raise alerts on its capital sufficiency.

The company priced its offering at 1 real per share, a 28.5% discount over Thursday's closing price of 1.40 real. The offering, initially set at 597 million shares, ended up increasing by 101% so IRB could raise the full amount it was looking for.

The offering was managed by the investment banking units of Banco Bradesco SA, Itau Unibanco Holding SA and Banco Santander Brasil SA. The pricing was first reported by local financial website Brazil Journal, citing sources.

Shares in IRB had fallen 65% so far this year by Thursday's close, and were hovering at all-time lows, according to Refinitiv data.

IRB entered a downward spiral in 2020, when Rio de Janeiro-based asset manager Squadra Investimentos uncovered accounting irregularities at the company, forcing a management overhaul.

In April 2022, a former senior executive was charged with fraudulently planting a false story that Warren Buffett's Berkshire Hathaway Inc had made a significant investment in the company.

Earlier this week IRB announced a deal to sell its Rio de Janeiro headquarters for 85 million reais, and a separate out-of-court agreement to receive 100 million reais to resolve lawsuits related to the Casashopping venture in Rio.

($1 = 5.2416 reais) (Reporting by Peter Frontini and Gabriel Araujo; Editing by Sandra Maler and Jan Harvey)