Cigarette packs in Thailand will be 85 percent covered with graphic health warnings and a quit smoking hotline telephone number by September, the public health ministry said on Friday.

The ministry issued its announcement a day after a Thai court gave the green light for the new regulation and days after regional neighbor Indonesia, one of the world's biggest tobacco markets, began printing graphic health warnings on packets.

Narong Sahametapat, permanent secretary for public health, said the regulation would help reduce the number of smokers in the Southeast Asian nation and deter others from starting.

"This will help our campaign to lower the number of smokers in Thailand. We will start checking tobacco retailers from September onwards to make sure they comply," Narong told reporters.

International tobacco companies last year sued the Thai government after the health ministry ordered an increased in the size of the warnings to 85 percent of packs from 55 percent.

A court temporarily suspended the measure but, on Thursday, the Supreme Administrative Court ruled it could take effect.

Lung cancer rates are on the rise for both men and women. The disease has become a leading cause of death in Thailand, where a packet of cigarettes costs, on average, less than the equivalent of US$3.

Opponents of the regulation say the warnings are ineffective and Thais are aware of the health risks associated with smoking.

Australia introduced strict packaging rules in 2012, with a combination of photos of smoker illnesses overlaid on plain brown packs with no branding or logos. The country is being closely watched for signs of success as others, including Britain and New Zealand, explore similar measures.

Tobacco use is among the leading preventable causes of death in the world, according to the World Health Organization, killing nearly six million people every year.