The Congress has demanded probe by Commission of Inquiry by a sitting Supreme Court judge into the Scorpene submarine project leak .<br/><br/>Briefing media in New Delhi this evening, party spokesman Randeep Singh Surjewala said, there should also be a complete security audit of the Defence Ministry. <br/><br/>Describing the leak as a threat to national security, he said, the government should fix the responsibility instead of covering up the episode.