Israel's Foreign Ministry says it's "unfortunate" that Philippine President Rodrigo Duterte chose to invoke Adolf Hitler and the Holocaust in his bloody anti-crime war.

Spokesman Emmanuel Nahshon said on Saturday that Israel is convinced the Philippine president "will find a way to clarify his words."

On Friday, the outspoken Duterte said "Hitler massacred 3 million Jews ... there's 3 million drug addicts. There are. I'd be happy to slaughter them."

"If Germany had Hitler, the Philippines would have...," he said, pausing and pointing to himself.

"You know my victims. I would like (them) to be all criminals to finish the problem of my country and save the next generation from perdition."

Duterte, under fire for extra-judicial killings in the drug war, was referring to the estimated number of drug addicts in the country. The U.S. has warned the president's violent rhetoric could affect aid.

The leader was voted to power in a May election on the back of a vow to end drugs and corruption in the country of 100 million people. He took office on June 30 and over 3,100 people have been killed since then, mostly drug users and peddlers, in police operations and in vigilante killings.