The Law Society will seek permission to intervene in a landmark dispute between the Serious Fraud Office and mining company the Eurasian Natural Resources Corporation which could reset the parameters of legal professional privilege.

The case, which is due to be heard by the Court of Appeal, is considered to be a crucial test in that it could result in internal documents relating to criminal investigations being handed over to prosecutors.

A high court ruling handed down in May, went in favour of the SFO. The watchdog, which has alleged bribery and corruption against ENRC, claimed that documents prepared for ENRC’s own internal investigation should not be covered by privilege.

ENRC, which strenuously denies the bribery and corruption allegations, said the High Court’s decision seemed to penalise it for responsibly taking steps to investigate the allegations so that it could properly understand what had happened and what should be done.

Joe Egan, president of The Law Society, said: ‘Without the protection of legal professional privilege, firms may find it difficult to conduct effective internal investigations. If the ruling is upheld, it potentially has the perverse effect of discouraging firms from self-reporting for fear of the consequences.

‘The right for anyone to communicate confidentially with their lawyer is a fundamental part of our legal system and we want to ensure that this right is protected for all of us, including corporations.’