Philippine President Rodrigo Duterte apologized on Tuesday for failing to save an elderly German hostage who was beheaded by militants, but insisted ransoms should not be paid. The Abu Sayyaf, a kidnap-for-ransom network in the southern Philippines, killed Jurgen Kantner, 70, on Sunday after its demands for 30 million pesos ($600,000) were not met. Addressing the German government and Kantner's family, Duterte said he was "very sorry" about his death and that the military had stepped up an offensive against the Abu Sayyaf in an effort to save him. "We really tried our best. We have been there. The military operation has been going on for some time already but we have failed. That has to be admitted," Duterte said. "But it's a matter of policy that we do not surrender to the demands of paying ransom. It will just increase the numbers," he said, referring to the militants. Meanwhile, Philippine President Rodrigo Duterte said on Tuesday he would recall some police to fight his controversial war on drugs, nearly a month after suspending the entire force from all operations in the bloody campaign. In an about-face on his decision to remove the 160,000-member Philippine National Police (PNP) from his signature campaign, Duterte said the country was beset by security and law enforcement challenges and he needed more manpower to sustain the crackdown on drugs. Duterte has been scathing in his criticism of police corruption after it was discovered that rogue drugs squad officers had kidnapped and killed a South Korean businessman at PNP headquarters. After banishing police from the anti-drug campaign, Duterte handed the lead role to the Philippine Drug Enforcement Agency (PDEA) and has called for the military to provide firepower for its operations. On Tuesday, he said those police recalled to operations would have to be supervised by PDEA agents. "So, I need more men. I have to call back the police again to do the job most of the time on drugs, not everyone," he told reporters. "And it's meant to be PDEA-supervised, whether done by the military or the police. There should always be a PDEA ... who will be supervising everything." Since the Jan. 30 police suspension, the drug trade has come back out of the shadows, more than half a dozen drug users and dealers in some of Manila's toughest areas told Reuters. PNP chief Ronald dela Rosa said on Monday drugs had returned to the streets in the past few weeks and police were ready to rejoin the campaign because "the sooner we return, the better." The war on drugs has caused international alarm, with 7,700 people killed since it was launched eight months ago, some 2,555 in operations in which police said suspects resisted arrest. Authorities strongly reject allegations by human rights groups that many of the other deaths were extrajudicial killings carried out by police, or hit men working for them. Duterte has resolutely defended the campaign and lambasted anyone who raises concern about it, including world leaders like then UN Secretary General Ban Ki-moon and former US President Barack Obama. He has promised to humiliate anyone who is willing to debate him on the issue. — Agencies