PHNOM PENH, Cambodia (AP) — Thirty-three pregnant Cambodian women hired to act as surrogate mothers were formally charged with surrogacy and human trafficking offenses.

The women, who were arrested last month when police raided the illegal business, were charged Friday at the Phnom Penh Municipal Court under a law that specifically targets surrogacy, which was outlawed in 2016 as Cambodia was becoming a popular destination for would-be foreign parents seeking women to give birth to their children.

Acting as an intermediary between an adoptive parent and a pregnant woman carries a penalty of one to six months in prison. The human trafficking offense is punishable by seven to 15 years' imprisonment.

A Chinese man and four Cambodian women accused of managing the business were charged last week with the same offenses. The Chinese man allegedly hired the women, who were put under the care of the Social Welfare Ministry following their arrests.

Developing countries are popular for surrogacy because costs are much lower than in countries such as the United States and Australia, where surrogate services can cost around $150,000. The surrogacy business boomed in Cambodia after it was put under tight restrictions in neighboring Thailand. There also were crackdowns in India and Nepal. After Cambodia's crackdown, the trade shifted to neighboring Laos.

In July last year, a Cambodian court sentenced an Australian woman and two Cambodian associates to 1 1/2 years in prison for providing commercial surrogacy services.