France's third-biggest listed lender said merging the two networks would save more than 350 million euros ($424 million) in costs in 2024 and nearly 450 million euros in 2025.

"The network will thus transition from about 2,100 branches at the end of 2020 to about 1,500 at the end of 2025," it said.

The bank also said its online bank Boursorama was targeting 4.5 million clients in 2025 from 2.5 million in 2020.

"Having won more than 2 million customers in five years, Boursorama intends to continue its investments aimed at onboarding new customers over the next few years," SocGen said.

Boursorama is expected to post a cumulative loss of about 230 million euros until 2023, the lender added.

The online unit expects a net income of 100 million euros in 2023 and 200 million euros in 2025.

SocGen Chief Executive Frederic Oudea has accelerated initiatives to overhaul the bank to boost its profitability.

The bank put its equity and credit structured products businesses under review earlier in the year after overall operations were hit by market volatility and dividend cancellations due to the coronavirus crisis.

SocGen has also exited in recent years areas where it lacked scale, selling units and activities in eastern and central European countries such as Poland, Bulgaria and Albania.

($1 = 0.8248 euros)

(Reporting by Matthieu Protard; Editing by Edmund Blair, Kirsten Donovan)