SINGAPORE (AP) -- Singapore's graphic anti-smoking TV ads are working -- but now will be aired only at night following complaints that they're too disturbing for children, officials said Thursday.

In one of the government Health Promotion Board's ads, a sunken-eyed woman with cracked lips and brownish, deformed teeth appears under the headline: "Quitting is hard. Not quitting, is harder."

The board said the three-month campaign that began March 20 will continue, but the ads now will only be shown after 8 p.m local time and will be preceded by a message warning viewers of the graphic content.

"The Health Promotion Board has received feedback that our advertisement may be too disturbing to some children," the board's chief executive, Lam Pin Woon, wrote in an open letter published Thursday in The Straits Times newspaper.

"Since the launch of our campaign, we have seen a fivefold increase in the number of calls to (the government's) QuitLine from smokers desiring to quit smoking," Lam wrote. "We encourage parents to take this opportunity to educate their children on the fatal consequences of smoking."

As part of the campaign, the board also has posted two actors -- posing as a doctor and a woman hacking and coughing on her deathbed -- in its bustling downtown business district at lunchtime.

Like Hong Kong, tightly controlled Singapore has banned smoking in most public places.

The city-state is well known for government-led public behavior modification campaigns that have included pushes for courteous driving, showing up on time for weddings, keeping public toilets clean and speaking proper English.

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