Their bid came on the final day of a three-day trip by Zhang Dejiang, who chairs China's communist-controlled legislature, where frustrated protesters have been kept out of sight behind barricades in a security lockdown.

Zhang's visit is the first by such a senior official for four years and comes as concerns grow that freedoms are under threat in semi-autonomous Hong Kong as China tightens its grip.

Police chased the group of five protesters as they ran along a major highway in eastern Hong Kong which had been cleared for Zhang, with Wong carrying a sign calling for "self-determination".

The group were detained before Zhang's motorcade emerged from the motorway tunnel.

The protesters were all members of Demosisto, a political party led by Wong, who became the face of major pro-democracy rallies in 2014.

A video posted on the party's Facebook page showed the group being chased on foot and pinned to the ground by traffic police.

"(Protesters) rushed out near the tunnel front to voice out the demand of self determination and the anger of people against the interference of the Chinese government," Demosisto's Agnes Chow said in a statement.

Demosisto confirmed five of its members, including Wong and fellow high-profile young activists Nathan Law and Oscar Lai, were detained by police after the incident.

Hong Kong police had no immediate comment.

Zhang's visit was ostensibly for an economic conference, but has been widely seen as a conciliatory effort after frustration over lack of political reform sparked a fledgling independence movement, condemned by authorities in both Hong Kong and mainland China.

During the trip, Zhang sought to reassure Hongkongers the city would not be "mainlandised" but hit back at activists calling for more autonomy, labelling them separatists.

Activists said Zhang had not seen the real situation in Hong Kong due to the major security clampdown, which saw seven arrested for unfurling protest banners on hills and flyovers.

However, in an address to local tycoons, businessmen and officials Thursday morning, Zhang insisted he saw the city's residents were "full of happiness" during his trip.

"What I have seen is their faces which are full of happiness and comfort," he added.

He said he had listened to pro-democracy lawmakers during a rare meeting, but reminded his audience Thursday that Hong Kong's economic success was "due to the fact that it is backed by the mainland".

Zhang later visited a home for the elderly and boarded a plane leaving Hong Kong Thursday afternoon.

Hong Kong is semi-autonomous after being handed back to China by Britain in 1997 and enjoys freedoms unseen on the mainland, but there are concerns Beijing's interference is growing in a range of areas, from politics to education and the media.