President Hu Jintao (R), chats with workers during his visit to Kai Tak. Photo: Reuters.

The incident happened when Mr Hu was paying a visit to the Kai Tak Cruise Terminal and Kowloon East development projects that are under construction.

The Apple Daily reporter asked Mr Hu whether he'd heard the wishes of Hong Kong people to vindicate the June 4 democracy movement.

Mr Hu didn't answer the question. Instead, the reporter found himself facing 15 minutes of questioning by police, after they removed him from the area. He later said the police told him he was "too loud" when asking the question, and had disrupted public order.

The police expressed regret over the incident, calling it "an isolated case".

In a statement, a spokesman said an undercover policeman was concerned the reporter was about to disrupt order and so asked him to leave the scene.

The spokesman said the reporter was allowed to go once his identity was confirmed. He said the police would investigate the incident further.

The chairwoman of the Hong Kong Journalists Association, Mak Yin-ting, criticised the police for interfering with press freedom.

After a brief stay at Kai Tak, President Hu told reporters the development projects were meaningful as they had considered both the economic development and livelihood needs of Hong Kong people.

The president went on to visit an unfinished public housing estate nearby.

Mr Hu's on a three-day visit to the territory to mark the 15th anniversary of the handover.