China has lodged representations to Singapore, requesting it cooperates with the Hong Kong government on the follow-up work over armored vehicles detained by Hong Kong customs, Foreign Ministry spokesman Geng Shuang said on Monday.

China asked the Singaporean government to observe the one-China principle, Geng said.

China has requested that Singapore strictly abide by the laws of the Hong Kong Special Administrative Region, he said.

"The Chinese government has always firmly opposed countries that have diplomatic ties with the Chinese mainland to conduct official exchanges of any kind with Taiwan, including military exchanges and cooperation," the spokesman reiterated.

Geng's remarks came after Hong Kong customs intercepted nine armored carriers belonging to Singapore on Wednesday.

According to China Central Television, the vehicles were in a cargo ship from Taiwan and transiting through Hong Kong. The vehicles were on their way back to Singapore from an earlier drill in Taiwan.