Pham Thi Hue, 35, and Ninh Thi Hai Yen, 31, are being questioned for "organizing surrogacy for commercial purposes."

Hue told investigators that when she was working in China in 2017 she met a man who identified himself only as Yang and as the director of a hospital.

Hue agreed to his proposal to bring women from Vietnam to act as surrogate mothers for VND50-60 million ($2,100-2,500) each plus a VND3-4 million a month to take care of them.

She returned to Vietnam and through social media found 11 women who agreed to go to China with her, including Yen.

It turned out that Yen was incapable of having a baby, but she found five others for Hue.

Between March and October last year Hue took the 15 women to a hospital in Guangzhou Province in China.

In November last year, Yang sent Hue back to Vietnam along with some of the women, who were pregnant by then.

Hue rented a three-story house in Ha Long town in the border province of Quang Ninh for them to stay.

Last month the police raided the apartment and discovered the women. No information has been revealed on how the police tracked them down.

Hue told them she had received VND260 million ($11,216) for the 15 women and had given Yen VND30 million.

It had been agreed that each of the surrogate mothers would get VND300-400 million after delivering the babies.

Police also found out that Yen was involved with another ring and had found five other woman for surrogacy in China and got VND150 million for it.

Vietnam legalized surrogacy since 2015 to benefit infertile couples, but not on a commercial basis and couples can seek help only from family members. Commercial surrogacy is punishable by up to five years in prison.

The country’s first baby born to a surrogate mother was in 2016 in Hanoi. The mother of the girl was unable to conceive after 18 years of marriage due to congenital abnormalities.

Cases of Vietnamese pregnant women being lured to China to sell their newborns are not rare.  

China, the world’s most populous country, suffers from one of the most skewed gender rates in the world due to its one-child policy and illegal abortion of female fetuses. This has been a major reason for the trafficking of Vietnamese women and girls over the border, and now, surrogacy.