Police have smashed a gang suspected of illegally offering ultrasound fetus gender tests from the backseat of a car in Wuhan, in central China's Hubei province, it was announced on Tuesday.

A 44-year-old woman, surnamed Hu, was arrested on March 29 after a pregnant woman reported she had received a fetus gender identification from her in a private car, police with Wuhan's Bureau of Public Security, said.

A man was also fined heavily.

According to a report from Yunmen county, Hu's arrest is a significant breakthrough. The gang operated by touring Wuhan with two ultrasound devices in a car.

Pregnant women are introduced by middlemen before undergoing the test which takes just a few minutes.

Hu is suspected of conducting the tests while other gang members made sure that nobody approached the car.

Each pregnant woman paid 500 yuan ($79) for the test and 200 yuan to the middlemen.

Police have also fined a man, surnamed Peng, 100,000 yuan after he confessed to acting as a middleman.

The pregnant woman, surnamed Wang, was attacked by Hu's husband and another four men as she left the police station on March 29 after making her report.

This is the third time Hu has been implicated in illegal fetus gender tests in the area, according to authorities with the Hubei Provincial Population and Family Planning Commission.

She was imprisoned for six months in 2010 for running the tests.

With no medical qualification, she probably used ultrasound devices when she was a trainee nurse several years ago.

China's sex ratio at birth is skewed toward male babies.

Ultrasound technology was first used for identifying the gender of fetuses in the 1980s. Though it is illegal in China for medical institutions or individuals to determine the sex of a fetus, unless it is medically necessity, some parents have tried to find out the gender of their babies and then abort female fetuses.

"Illegal ultrasound fetus gender identification is the chief culprit for the imbalance," said Shu Qinghua, director of the Yunmen County Population and Family Planning Bureau.

"Offenders get off too lightly."

Xinhua in Wuhan