BANGKOK (AFP) - A Chinese couple and seven Thais were arrested in Thailand on Thursday (Feb 13) charged with violating a law banning surrogacy for foreigners, Thai police said.

The former military junta outlawed the practice in 2015 after a string of scandals in a country that was once a hub for international surrogacy.

Thai police made the arrests in raids on several houses and offices in Bangkok and the central provinces of Patumthani and Sukhothai, police told reporters at a Bangkok press conference.

They found eight surrogate mothers, including one who was eight months pregnant, and also "saved" a 22-day-old baby boy and a four-month-old girl, police said.

They suspect up to 14 more children have already been trafficked to China.

"This is a transnational crime," said Major General Worawat Wattananakhonbanch.

"They planted the sperm in a neighbouring country, provided antenatal care in Thailand and then the mothers gave birth in China."

Thailand for years hosted a thriving yet largely unregulated international surrogacy industry popular with same-sex couples.

But a string of scandals in 2014 - including tussles over custody - spurred the military government to bar foreigners from using Thai surrogates.

One case saw an Australian couple accused of abandoning a baby with Down's syndrome carried by a Thai surrogate while taking his healthy twin sister.

In another high-profile controversy, authorities discovered nine babies in a Bangkok apartment fathered by a Japanese man using Thai surrogate mothers.

Police expanded their investigations into surrogacy since 2017 when a man was arrested for trying to smuggle six vials of sperm into Laos, Police Colonel Mana Kleebsattabutra added.