BEIJING • China is concerned over the Philippines' detention of more than a thousand Chinese nationals during a crackdown on online gambling, the Foreign Ministry said yesterday, in what could be a strain for ties that have warmed in recent months.

The Philippines' immigration bureau last week detained about 1,200 Chinese people working in call centre-like facilities suspected of running online gambling operations out of a former US air base, Clark Field.

The detentions marked Manila's biggest such round-up of Chinese nationals in the country, many thought to be working there illegally.

Chinese Foreign Ministry spokesman Geng Shuang said Beijing had requested that the Philippines "appropriately make arrangements" for those who had been detained and quickly release individuals who have "legal identification".

"At the same time, China expresses concern over the large number of Chinese citizens detained by the Philippines," Mr Geng told reporters at a regular press briefing.

It is unclear if the Chinese nationals were being held for gambling offences or for visa and immigration violations, but about 900 were taken to the immigration detention centre in Manila, according to a Philippine police report.

Online gambling is not illegal in the Philippines, but it is subject to permit and zoning regulations.

China has expressed support for the Philippines' other law enforcement efforts, including President Rodrigo Duterte's anti-narcotics campaign, which has sparked criticism from Western countries over fears of extrajudicial killings.

REUTERS