Shenzhen customs officials show the blood samples seized at a checkpoint. [Photo/chinanews.com]

Customs officials in Shenzhen, South China's Guangdong Province, have seized 262 blood samples of pregnant women from the mainland in four shipments destined for neighboring Hong Kong for gender tests.

In one case on July 25, officers at Futian Checkpoint, a major link with Hong Kong, found 203 blood samples in a woman's bag. In another case, a passenger hid the tubes in her bra in an attempt to escape detection.

Suspects caught said they were paid between 100 yuan ($14) to 300 yuan for smuggling the blood samples.

An official at Huanggang Customs said many mainland parents want to know the gender of their expected child before deciding whether to give birth. It's illegal to have prenatal gender tests for non-medical purposes on the mainland, so some agencies take blood samples from pregnant women and transport them to Hong Kong for tests.

Huanggang Customs said it will intensify checks against illegal transport of blood samples through a number of measures, vowing to end the "profit chain."

Blood samples set for gender test are seized. [Photo/Chinanews.com]