More than 1,900 people, or about 36 per day, have been killed in a violent campaign against drugs in the Philippines since President Rodrigo Duterte came to office seven weeks ago, the country's national police chief said on Tuesday. Director General Ronald dela Rosa told a Senate hearing there was no declared policy to kill drug users and pushers and that about 1,100 deaths were still being investigated. "We are not butchers," he said. The rest of the dead were people killed in police anti-narcotics operations, dela Rosa said. "This has a chilling effect," said Senator Frank Drilon after the police chief's deposition. "We are all concerned about the number of deaths, by any language this is alarming." Duterte, nicknamed "the Punisher", was voted to power promising to wipe out drugs and warning traffickers they risked death if they did not mend their ways. The inquiry is being conducted by a staunch critic of the president, Senator Leila de Lima, who has summoned top police and anti-narcotics officials to explain the "unprecedented" rise in the body count and reports of vigilante killings. Duterte has warned legislators not to interfere with his campaign, saying they could be killed if they blocked efforts aimed at improving the country. Nearly 700,000 drug users and drug peddlers have turned themselves in to escape the crackdown, police chief dela Rosa said. He said there was a decrease in overall crime, although murders and homicides had increased. Outside the senate building, dozens of supporters cheered dela Rosa for leading the war against drugs, chanting his nickname, "Bato, Bato". Dela Rosa said about 750 of the dead were killed in police operations against drug peddlers. The other deaths were being investigated, he said. "Not all deaths under investigation are drug-related," dela Rosa said, adding that 40 killings were known to be due to enmity or robbery. He also said about 300 of his officers were suspected to be involved in the drugs trade, warning these personnel will be sacked and charged in court if found guilty. There has been speculation in the local media that some of the killings were carried out by corrupt police officers who were wiping out drug peddlers to avoid exposure.