Suspects involved in serious crimes against Chinese citizens in Angola are escorted off the plane after arriving in Beijing Capital Airport Saturday morning. Qi Heng / Xinhua

Thirty-seven Chinese nationals who allegedly carried out violent crimes and forced young Chinese women into prostitution in Angola were brought back by Chinese police on a chartered flight on Saturday, according to the Ministry of Public Security.

The 14 Chinese female victims also arrived in Beijing from Luanda, the capital of Angola on the same flight, the ministry said.

In early August, Chinese police cooperated with their Angolan counterparts to crackdown on 12 Chinese criminal gangs, which targeted Chinese in Angola. The gangs were involved in kidnapping, robbery and extortion. They allegedly abducted the Chinese girls to provide sex, according to the ministry.

The police uncovered 48 major criminal cases in addition to rescuing the 14 Chinese women, the ministry said.

"This is the first large-scale campaign by Chinese police against criminals targeting Chinese victims in Africa," said Liu Ancheng, director of criminal investigation department of the ministry.

"The joint law enforcement action opened a new chapter in the police cooperation between China and Africa, and will safeguard the safety and other legitimate rights of Chinese citizens and institutions in Angola," he said.

In January, the Chinese embassy in Angola reported that since 2011, violent crimes targeting Chinese, including robbery, kidnapping, extortion and forcing Chinese girls into prostitution frequently happened in Angola, the ministry said.

In April, Angola's Interior Minister Sebastiao Martins paid an official visit to China to sign a cooperative agreement with Meng Jianzhu, China's minister of public security, aimed at maintaining security and social order.

They discussed the criminal activities targeting Chinese victims in Angola, and agreed China would immediately dispatch a team to Angola so investigators from both countries could jointly pursue relevant cases and evidence of crimes.

The police say their investigation shows that since 2009, the Chinese suspects were colluding with locals to target Chinese.

Victims were variously beaten up, doused with gasoline, and buried alive to extort ransom.

"Some suspects cheated these naive girls from rural Chinese regions under the guise of introducing them to work abroad in good environments and high salaries," said Chen Shiqu, director of anti-human trafficking office of the criminal investigation department under the ministry.

In July, the ministry appointed Liu Ancheng as commander and deployed more than 30 police officers from regions including Liaoning, Anhui and Fujian, and established the joint operations command with Angolan police.

"We overcame various obstacles, including language and differences in law and folk customs to effectively develop the investigation," Chen said.

Angola organized 400 armed police for the joint action, which Chen says neutralized 12 criminal gangs and netted 37 suspects.

Meanwhile, another 24 suspects were detained in China by national police authorities.

When political difficulties seemed to be preventing the repatriation of the suspects, Meng wrote a letter to Martins seeking legal assistance, and on Saturday the 37 suspects were handed over and escorted to Beijing.

Since China's opening-up , more Chinese are working and traveling overseas, Liu said, and the number of criminal cases targeting Chinese is on the rise.

The successful crackdown should be a strong deterrent against attacks on Chinese nationals aboard, he added, and it demonstrates the resolution of the Chinese government to protect its citizens overseas.

Zhangyan1@chinadaily.com.cn