The Sri Lankan government on Monday defended its decision to declare several key locations in Colombo as high-security zones, saying the move is aimed at ensuring stability and not curbing freedom of expression, amid mounting criticism from rights groups.Sri Lankan President Ranil Wickremesinghe on Friday declared several locations, including Parliament, the Supreme Court complex and the Presidents Secretariat among others, as high-security zones HSZs, banning any kind of protest or agitation in their vicinity.HSZs are nothing new.