The Australian Securities and Investments Commission was in court yesterday, for the first stage of an action against NAB over allegations of interest rate rigging. ASIC told the court it had served four statutory notices on NAB, seeking documents and telephone conversations about whether bank employees had been told not to engage in conduct to influence the benchmark rate.But NAB is fighting access by the regulator, reports the AFR. "We have already produced over ten million documents so far," NAB barrister David Thomas told the judge."The other banks didn't have to provide it ... it travels beyond the issues in dispute [and] these are complex and difficult issues", he said.The action follows on from an announcement earlier this month by ASIC that it was launching legal action against NAB as part of the corporate regulator's multi-part crackdown on major banks.This prompted NAB's group chief risk officer, David Gall, to claim: "NAB has fully co-operated with ASIC's review and takes these allegations seriously. We do not agree with ASIC's claims which means they will now be settled by a court process."His statement also noted that, "as part of ASIC's investigation NAB has provided emails, instant chat messages and telephone conversations involving our employees. NAB retains this information as part of our business processes."Further back - about 16 months ago - ASIC fronted the Senate Estimates Economics Committee and said investigations into bank bill swap rate manipulation were "at an advanced stage."In response ANZ, Westpac, and NAB had confirmed that they were cooperating with ASIC's investigation."Hearing the ANZ case is likely to lead to the resolution of the other cases," ASIC lawyer, John Karkar QC, told the court.The case continue with hearings this week and a joint case management hearing scheduled for August on August 22 and a tentative trial date for August next year, the AFR reports.