BEA Systems, the embattled US software group, said on Monday said it would allow Carl Icahn, the activist investor, access to confidential information in an effort to defend its decision to reject a $6.7bn offer from Oracle.

Mr Icahn and BEA have signed a non-disclosure agreement that will allow the veteran activist a period of “due diligence” at the company, in which he holds a 15 per cent stake.