A number of cross-border drug trafficking channels and distribution centers have been broken up in South China's Guangdong province after a crackdown in the first five months of 2018 that dealt with 4,655 drug and related cases, a senior police officer said.

Lin Weixiong, deputy director of the province's Public Security Department, said police seized more than 5.4 metric tons of narcotics, mostly crystal methamphetamine and ketamine, between January and May, up from 5.1 tons in the first five months of last year.

"Meanwhile police detained 5,504 suspects, including suspected foreign drug traffickers, dealing a heavy blow to drug and related crimes," Lin told a news conference in Guangzhou, the provincial capital, on Wednesday.

He said the fight against drug crime in Guangdong has achieved "significant results", with the number of drug cases falling.