By Manuel Mogato

MANILA (Reuters) - Philippine President Rodrigo Duterte said on Wednesday his government is willing to face any inquiry into the deaths of hundreds of suspected drug dealers and users as human rights groups express alarm over extrajudicial killings.

Nearly 600 suspected drug peddlers and users have been killed in police operations since Duterte took power six weeks ago, police say, but rights groups put the number at more than 1,000.

"We are willing to submit ourselves for an investigation before anybody," Duterte said in a speech at the national police office, adding some of the killings were carried out by drug gangs.

"But do not attribute acts of other criminals upon my government. The fight against drugs will continue unrelenting until we have destroyed the apparatus operating in the entire country."

There have been cases when police officers have killed suspected drug dealers in handcuffs, in police custody or inside prison cells, civil rights lawyers have said. Police have said they will not condone wrongdoing but that some may have been killed by rogue officers.

In another public event, Duterte attacked Senator Leila de Lima, who will open a public inquiry next week into drug-related killings, saying she was only playing politics and linked her driver to the drugs trade.

"It's character assassination," an emotional de Lima told reporters at the Senate. "It's so foul. I did not expect the president to do that."

Duterte won the presidency in May on a single platform of suppressing crime and drugs, declaring war on narcotics on his first day in office. He has identified 160 officials, police and judges in a name-and-shame campaign to stop the drug trade.

"I myself, who ordered the campaign against drugs, take full and sole responsibility for it," Duterte said, cautioning police against using excessive force in making arrests.

"Do not kill if you're not in danger of losing your life."

(Editing by Nick Macfie)