SHANGHAI (REUTERS) - The police in China have broken a child trafficking ring that they say has been selling children from the remote south-west to buyers near the coast 2,000km away for as little as about US$3,000 (S$4,300), the state news agency Xinhua has reported.

The police had caught 78 suspects and rescued 15 infants, the report late on Wednesday (Jan 20) said.

Xinhua said the police spotted a suspicious couple in September who travelled frequently between the mountainous town of Liangshan in Sichuan province and the city of Linyi in Shandong province near the coast.

"The wife purchased infants in Liangshan, and transported them to Linyi. The husband was responsible for seeking buyers in the city," it said, quoting the findings of the investigation.

Baby boys were sold for 50,000-60,000 yuan (S$10,900-S$13,100), while girls were sold for 20,000-30,000 yuan, Xinhua quoted police as saying.

The rescued infants were being cared for by a local civil affairs department. Doctors had taken blood samples to help find their biological parents, Xinhua reported.

The investigation was continuing but Xinhua did not give further details.

Child trafficking is rampant in China, where population control policies, although recently relaxed, have bolstered a traditional bias for male offspring, seen as the main support for elderly parents and heirs to the family name, and have resulted in abortions, killings or abandonment of girls.

The imbalance has created criminal demand for abducted or bought baby boys, but also for baby girls destined to be future brides attracting rich dowries.