The bank had already downsized its proprietary trading operations following the 2008 financial crisis in a bid to reduce exposure to market volatility.

The bank held the operation in a distinct legal entity called Opera to comply with local banking regulations that ban French banks from directly trading on markets with their own funds. They are only allowed to do market-making for clients.

Regulators in France, like in other countries, have toughened rules to prevent banks from speculating on markets with funds from depositors.

BNP Paribas didn't disclose Opera's performance, but has said the entity handles 600 million euros (536 million pounds) in capital.

The unit is not significant for the bank's operations and only employs 17 people, mainly in London and Paris, the source said.

(Reporting by Inti Landauro and Matthieu Protard; Editing by Leigh Thomas and Geert De Clercq)