(Reuters) - U.S. and UK regulators are expected to announce a civil settlement as soon as Thursday of their investigations into JPMorgan Chase & Co's (JPM) "London Whale" derivatives loss, a source familiar with the matter said on Wednesday.

The settlement, which is expected to be for at least $700 million, would resolve several civil probes into the multibillion-dollar trading losses at the largest U.S. bank last year. Regulators, including the U.S. Securities and Exchange Commission and the UK's Financial Conduct Authority, are expected to be part of the settlement.

The New York Times reported that the fines would top $900 million.

The FCA and SEC declined to comment.

However, U.S. prosecutors are still investigating JPMorgan for potential criminal wrongdoing.

A settlement would mark a key step in JPMorgan's efforts to resolve its regulatory and legal troubles. The bank is facing separate probes by various government agencies into areas that include possible bribery in hiring practices in China and potentially fraudulent sales of mortgage securities.

Following the "Whale" scandal, Chief Executive Jamie Dimon faced a bruising battle with some shareholders to retain his chairman title and has since been under pressure to improve the bank's relationship with regulators.

Two former bank employees - Javier Martin-Artajo and Julien Grout - have already been charged with trying to hide some of those losses by deliberately giving inaccurate values to the sophisticated securities involved in the trades.

Bruno Iksil, the trader whose large bets earned him the nickname "London Whale," has signed a cooperation agreement with prosecutors and has not been charged with any wrongdoing.

(Reporting by David Henry in New York and Huw Jones in London; Editing by Gary Hill)