South Korea has launched a campaign offering cash to men if they promise not to buy sex from prostitutes after year-end office parties, government officials said Tuesday.

The move is aimed at changing the party culture in this male-dominated society by winning commitments from male employees to abstain from hiring prostitutes after their parties finish, an official at the Gender Equality and Family Ministry said, asking not to be identified because of policy.

A total 4.6 million won ($5,000) will be paid to companies based on the largest number of volunteers who sign a written pledge, said the official. Some 1,300 companies have so far participated in the campaign that ends Tuesday.

South Korea has stepped up its crackdown on prostitution since 2004 when the legislature passed new anti-prostitution laws targeting human traffickers, pimps and prostitutes. Still, the practice remains widespread.

A government-funded study showed that South Korea's sex industry generated 4.1 percent of the country's gross domestic product in 2002 and employed 330,000 women. Some experts say the figures are grossly underestimated.

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