GUANGZHOU, April 30 -- Chinese police have arrested 16 members of a foreign gang allegedly involved in robbery and drug trafficking in the southern Guangdong Province, they announced on Thursday.

Police uncovered the mafia-style group when investigating a robbery in 2014, according to a statement from the public security bureau in provincial capital Guangzhou.

The group, established in 2009 and headed by two people named as Odunukwe Chinedu and Abdoulaye, is suspected of being involved in five robberies and two drug trafficking cases, said the statement, without disclosing the suspects' nationalities.

Eleven of the foreign suspects were detained and a large amount of drugs seized in February as about 100 police officers launched raids in Guangdong cities including Guangzhou, Foshan and Dongguan.

The other five suspects were arrested in Guangzhou and Dongguan on April 16, when another large quantity of drugs was seized.

According to the statement, investigation showed that they also used violence to help others take back loans and to force people to join their group.