Philippine President Rodrigo Duterte will this month ban smoking in public, the health department said Wednesday, further strengthening some of the toughest tobacco regulation in Asia.

The firebrand leader has waged a ruthless law and order campaign since July that has left more than 3,000 people dead while, as a long-time mayor of the southern city of Davao, he imposed curfews on minors and banned public alcohol sales at night and shirtless men.

The upcoming law is in addition to legislation banning tobacco advertising and regulating smoking in indoor public places, as well as a statute that requires graphic images of smoking health hazards to be printed on cigarette packaging.

"There has been a significant reduction in smoking, but the reduction has been slow," Assistant Health Secretary Eric Tayag told AFP.

"We want to have in place all the tools that are needed to expand this campaign," he added.

Tayag said the new drive was prompted by Duterte who, in 2002, banned smoking in all public places in Davao.

The World Health Organization said 20.6 percent of the Philippine population smoked as of 2013, 10 years after the tobacco regulation act was passed.

The country of 101 million also remained one of 15 nations worldwide with a heavy burden of tobacco-related ill health, the WHO said.

The existing law bans smoking in indoor public places including government buildings, hospitals and schools as well as public transport.

Bars and nightclubs are required to set aside designated , but smoking outdoors is not regulated.

Tayag said the planned executive order would plug that gap by only allowing smoking outdoors at the back of buildings "where there are no people".

It will authorise municipal and city governments to impose penalties that could include prison terms, fines, community service or a combination of the three, he added.