French bank shares suffered a fresh sell-off on Monday as concerns about the eurozone sovereign debt crisis intensified, despite an attempt by Société Générale to assuage market concerns by pledging to accelerate asset disposals and cut costs.

SocGen tumbled to a 20-year low of €14.80, down 10 per cent on the day and 70 per cent off its February highs. Shares in BNP Paribas fell more than 12 per cent to €25.41, while Crédit Agricole’s dropped 10 per cent to €4.65.

Broader eurozone bank shares also suffered, plunging to depths they only surpassed for three days in early 2009 during the financial crisis. They have now fallen 55 per cent since their peak in February. UniCredit and Intesa Sanpaolo of Italy were down 11 and 10 per cent respectively as Italian 10-year bond yields rose above 5.5 per cent again. Greek 10-year yields brushed close to 23 per cent as investors fretted about a possible default from Athens.