The Philippines' interior secretary asked around 300 of the country's top police officers to submit courtesy resignations on Wednesday in a bid to "cleanse" the force of links to the illegal drug trade.

A committee has been formed to assess the records of every police general and full colonel. Those found to be clean will be allowed to return to work, while those found guilty will have their resignations accepted.

"If you're not involved, there's nothing to worry about," Interior Secretary Benjamin Abalos told reporters at the national police headquarters near Manila.

Anyone who did not tender their resignation would be "questionable," he added.

Officers arrested in war on drugs

Filipino President Ferdinand Marcos Jr. has largely continued the controversial war on drugs launched by his predecessor Rodrigo Duterte.

Police arrested 30,000 people and killed around a dozen suspects since Marcos took office in June.

But these efforts have been hampered by a few high-ranking police officers who are involved in the narcotics trade, Abalos said.

Last year, more than a dozen officers were arrested or relieved from their posts because of proven or suspected links to the illegal drug trade.

"It appears that there is a big problem in our police force. It appears there are generals and colonels involved in drugs," Abalos said.

"It's difficult to fight a war when it's your ally that will shoot you in the back," he added.

In the past six months, authorities have confiscated 10 billion pesos ($179 million or €169 million) worth of methamphetamine alone.

zc/dj (Reuters, AP, AFP)