It will be "regretful" if National Security Advisor talks between Pakistan and India are cancelled on "flimsy grounds", Pakistan's NSA Sartaj Aziz said on Saturday.At a press conference here ahead of the talks scheduled to be held in New Delhi on Monday, Aziz said the purpose of the NSA talks was to achieve calm between the two countries.The international community will have to "carefully ponder if it was possible for India to cancel the talks on such flimsy grounds... if the regretful cancellation happens".Pakistan's high commission has invited Jammu and Kashmir's separatist leaders to meet Aziz ahead of his talks with his Indian counterpart Ajit Doval. India has advised against this.