More than 1,800 immigrants living in the country without legal permission have been detained in Guangdong province so far this year, a 40 percent increase on the same period last year.

Jiang Mingxiang, deputy chief of the province's border control police, said most of the migrants had come from Southeast Asian countries and were bound for Guangdong and Hong Kong to find work.

They could have impacted local security and border management if they had become involved in theft, robbery or drug trafficking, he said.

Police have also detained a number of factory owners who are accused of employing migrants, as well as several suspected people smugglers.

On March 5, Guangdong police jointly launched with their Hong Kong and Macao counterparts a half-year campaign aimed at cracking down on cross-border organized crime.