Fraud compounds where scammers lure internet users into fake romantic relationships and cryptocurrency investments have flourished across Southeast Asia, including in Cambodia and the lawless borderlands of Myanmar.

Initially largely targeting Chinese speakers, the criminal groups behind the compounds have expanded operations into multiple languages to steal billions of dollars from victims around the world.

They used thousands of foreign workers -- some willingly and some trafficked -- to carry out the scams.

In recent years, Beijing has stepped up cooperation with regional governments, and thousands of people have been repatriated to face trial in China's opaque justice system.

The latest announcement comes days after a court in the eastern Chinese city of Wenzhou said it had executed 11 people linked to telecom scam operations with the "Ming family criminal group".

The most recent four people executed were linked to the "Bai family criminal group", the Shenzhen Intermediate People's Court said in a statement.

Their crimes included "fraud, intentional homicide, intentional injury, kidnapping, extortion... (and) forced prostitution" among others.

One member, Bai Yingcang, "also colluded to sell and manufacture about 11 tonnes of methamphetamine", the statement said.

According to the court, the group ran fraud parks in northern Myanmar's Kokang region, where their actions led to the deaths of six Chinese citizens and injuries to "many" others.

The four were sentenced to death in November.

A fifth person also sentenced to death, Bai Suocheng, "died of illness" following the November verdict, the court said.

He was alleged to have been the group's ringleader.