The lawyer for Jérôme Kerviel – the man who allegedly masterminded the biggest rogue trading fraud in financial history – on Sunday accused his employer, Société Générale, of complicity in the scandal that has cost the bank €4.9bn ($7.1bn).

“The question we ask is can we really speak of fraud when it seems that everyone knew what Jérôme was doing?” said Guillaume Selnet. He insisted there was “no Jérôme Kerviel organisation. He is not at the head of some network,” implying that Mr Kerviel had worked alone but suggesting complicity on the bank’s part because it was aware of his trades.