New Zealand general insurer Tower has disclosed to the stock market that it is in talks with its insurance regulator, the Reserve Bank of New Zealand, about a possible increase in its minimal solvency margin to remain licensed as an insurer.The Reserve Bank was given the role of insurance industry regulator under the Insurance Prudential Supervision Act of 2010 and has set a deadline of September 7 for insurers to be fully licensed or cease to do business.The bank warned in June that it was taking a more stringent approach regarding insurers' licence applications as the final deadline neared.