Chief Executive of the Hong Kong Special Administrative Region (HKSAR) Carrie Lam said on Tuesday that the 12 Hong Kong residents detained on the Chinese mainland after they were intercepted by Guangdong coastguards on a speedboat "should be dealt with according to the mainland laws" before the SAR government could intervene.

"Because if these Hong Kong residents were arrested for breaching mainland offences, then they have to be dealt with according to mainland laws in accordance with the jurisdiction before any other things could happen," Lam added at a media briefing.

The 12 people, who are reported to have tried to flee to Taiwan last month, were arrested on August 23.

On August 26, the China Coast Guard announced that its Guangdong force had intercepted a vessel in Chinese waters off southeastern Hong Kong and arrested more than 10 people on suspicion of unlawfully crossing the border, and investigations were under way.