Apart from a brief afternoon recess, BNP Chairman Michel Pebereau, his Societe Generale counterpart, Daniel Bouton, and Paribas Chief Executive Andre Levy-Lang were holed up since 2:30 p.m. local time Monday with Trichet, who is seeking to devise a "consensual solution" to end the long-running takeover battle.

No details of the talks were released, but the three banks are understood to be discussing a proposal by Trichet, under which Societe Generale and BNP would remain as independent retail banks in France, but would pool a lot of their activities in a jointly held holding company that would also include much of Paribas. In its initial form, the plan is unlikely to be endorsed by the warring banks, say people close to the talks.

Thecompromise plan is an attempt to break the logjam created by two rival, incompatible bids. Societe Generale and Paribas were close to an agreed merger under which Societe Generale would absorb Paribas through a share-swap when BNP stunned the two banks by launching unsolicited bids for both banks in March. Societe Generale has since sweetened its offer for Paribas by adding a cash payment of up to 1.5 billion euros ($1.56 billion) to its all-stock offer, but the revised bid is till awaiting regulatory approval, and Trichet has asked the banks to use the additional time to seek an agreed outcome.

The move has been widely criticized as meddling in a market battle, and the combined market capitalization of the three banks has fallen by 6.5 billion euros in the past week. Paribas shares fell 1.8%, or 1.90 euros, to 104.10 euros Monday in Paris trading. BNP shares fell 1.6%, or 1.30 euros, to 78.50 euros, and Societe Generale shares slipped 1 euro, to 164 euros.