WASHINGTON – In a scathing report, Senate investigators said JPMorgan Chase & Co.’s huge trading losses last year were caused by high-risk market bets that bank executives failed to catch despite numerous red flags.

The 307-page bipartisan report released Thursday said the bank tried to hide the $6.2 billion of losses in the “London Whale” trades from regulators and the public. The report went on to criticize JPMorgan’s federal regulator, the Office of the Comptroller of the Currency, for failing to discover and properly investigate the trades.

The risky bets on complex financial instruments damaged the well-honed image of JPMorgan, the nation’s largest bank, and its chief executive, Jamie Dimon.

“We found a trading operation that piled on risk, ignored limits on risk-taking, hid losses, dodged oversight and misinformed the public,” said Sen. Carl Levin, D-Mich., chairman of the Senate’s Permanent Subcommittee on Investigations.