Banque Nationale de Paris (BNP) last night launched a hostile takeover bid for French banking groups Societe Generale and Paribas, currently in the process of merging, the Paris stock market announced.

If successful, BNP would become the largest bank in the world in terms of assets, likely to exceed €850 billion (£669 billion).

BNP has offered 15 new shares for seven shares in Societe Generale, France's biggest private bank, and 11 for eight Paribas shares. The offer is 14 per cent above Societe Generale's share value at yesterday's close, BNP said, and 18.3 per cent above Paribas' share value.

BNP will follow through on its bid if it succeeds in acquiring 50.01 per cent of the capital in Paribas and 50.01 per cent of voting rights in Societe Generale, it said.

The Paris stock market, which announced the approach late last night, has requested a suspension of all trading the banks.