Malaysia's National Police chief Khalid Abu Bakar on Monday said 139 grave sites and 28 suspected human trafficking camps were discovered near the country's northern border with Thailand."However, the authorities are still unable to confirm how many bodies are inside each grave," the police chief said.According to sources, the graves were believed to contain remains of refugees and foreign job seekers, Xinhua news agency reported.A crackdown on human trafficking was launched in Thailand after dozens of bodies of Rohingya migrants from Myanmar were exhumed from graves found in Thailand's side of the border in recent weeks.Since the crackdown, boats carrying thousands of migrants seeking to land in Malaysia, Indonesia and Thailand, mostly from Myanmar and Bangladesh, have been stranded at sea.Indonesia and Malaysia have later agreed to take on 7,000 Bangladesh migrants and Myanmar's Rohingya refugees pending their repatriation.