Manila: Philippines President Rodrigo Duterte has said that no one could stop him from declaring martial law if the drugs problem worsens in the country, the media reported."If I wanted to, and it will deteriorate into something really very virulent, I will declare martial law if I wanted to. No one will be able to stop me," Duterte said in a speech to business people in the southern city of Davao on Saturday.But the President said he would declare martial law not on the basis of invasion or insurrection but to preserve the country, Inquirer daily reported."The aim would be to preserve the Filipino people and the youths of this land," he said, adding that he is acting to prevent the country from becoming a narco-state."My country transcends everything else, even the limitations," he added.About 6,000 people have been killed in six months under Duterte's anti-drugs crackdown.Martial rule would allow Duterte to use the military to enforce civilian law and detain people at length without charge.The Philippines Constitution says a President can only declare martial law for 60 days and then only to stop an invasion or a rebellion. But Duterte said the 60-day limit "would be gone".However, his comments contradict remarks made in December when he appeared to rule out the use of martial law, saying it was "nonsense" and had not improved people's lives in the past.The President did not end his speech without slamming his critics, who claimed that he wanted to declare martial law to extend his term."Those in Manila thinking about martial law, lengthening your stay ...b*lsh*t," he said. "I do not need the presidency at this point in my life," he added.Duterte has vowed to rid the country of illegal drugs and his campaign has seen thousands die in police operations and unexplained killings by suspected vigilantes.About a million drug dealers and users have handed themselves in to police. The crackdown has led to international condemnation, with outgoing US President Barack Obama urging Duterte to prosecute his war "the right way".Some human rights lawyers say Duterte's support for a shoot-to-kill policy could make him vulnerable to prosecution for crimes against humanity at the International Criminal Court (ICC).