Groupama Insurances UK marine operation it to become part of the newly-created Groupama Transport Worldwide company.
The move is part of an efficiency drive which sees the consolidation of marine and transport activities under one roof.
The Groupama Insurances marine underwriting operation in London currently contributes £25 million to the £80m turnover of its parent.
Groupama Transport will operate from offices in France, and Hong Kong as well as London.
"We now have a clear and long-term strategy for the future of the marine business going forward in London," said head of marine underwriting Richard Norman. "We will continue to underwrite marine but will not chase the market. Instead we will concentrate on building quality relationships with our brokers to generate solid, profitable business.