Five people linked to the pro-independence group "Returning Valiant" were on Saturday sentenced under the national security law to detention at a training centre, an alternative to prison for offenders aged under 21.

They were among seven, aged between 16 and 26, who earlier admitted to conspiracy to incite others to subvert state power at the District Court, in a case marking the first time minors have pleaded guilty under the security legislation.

Designated national security judge Kwok Wai-Kin sentenced the five to the training centre, where the minimum sentence is six months and the maximum is three years.

The judge also adjourned sentencing for the remaining two defendants.

The court had heard that the group distributed leaflets at street booths and made remarks advocating an armed uprising as the only way to topple the government last year.