The helper who got kicked was former Eastern district councillor Dominic Wong Chi-chung, 46. He was helping out at a booth of his partymate Edward Leung Hei from the Democratic Alliance for the Betterment and Progress of Hong Kong, who is running in the Hong Kong Island East geographical constituency.

During the campaigning, a 49-year-old Vietnamese man approached Wong and kicked him in his forearm, while also damaging the promotion material in his hands.

According to a video widely circulated online, the man wanted the campaign team to move the promotional pull-up banner as it was blocking the streets, and the two then had a quarrel filled with obscene language.

The man also described the banner as rubbish multiple times, before suddenly kicking Wong’s left hand that was holding a promotion cardboard.

Police officers later arrived at the scene and arrested the Vietnamese man.

“The Vietnamese man was arrested for common assault, and Wong felt pain in his forearm and was sent to Eastern Hospital for treatment,” police said.

Leung and his party issued a statement shortly afterwards saying they strongly condemned violence, and called on the police to exert their utmost effort to investigate the incident which will ensure that promotion for the election can be done safely, orderly and fairly.

“We will soldier on fearlessly, and insist on walking into the community to listen to citizens. We also call on the society to say no to violence and safeguard a fair election to allow Hong Kong’s constructive force to return to the legislature,” they wrote.

Other candidates running in Hong Kong East include Stanley Ng Chau-pei from the Federation of Trade Unions, Marcus Liu Tin-shing from the New People’s Party and Jason Poon Chuk-hung, managing director of construction firm China Technology Corporation.

Meanwhile, Lau Siu-kai, vice president of the Chinese Association of Hong Kong and Macau Studies, said some pro-democracy politicians will eventually join the “patriotic system.”

Speaking in a television interview on Sunday, Lau said opposition politicians are just labeling themselves as non-pro-establishment as they dare not admit that they are patriots too soon, as they fear losing the trust from their pro-democracy supporters.

The nomination period for the December 19 Legislative Council election ended on Friday, with 154 candidates racing for 90 seats, and for the first time after handover in 1997 all the constituencies will see competition.