US video hosting service YouTube on Wednesday suspended a channel promoting John Lee's uncontested bid to be Hong Kong's next leader, saying the move was in compliance with sanctions against the ex-security chief.
Lee is expected to be appointed the business hub's new chief executive by a committee of 1,500 Beijing loyalists next month. He faces no rivals.
But he has nonetheless worked to promote his campaign with a presence on Facebook and YouTube.
Lee condemned the US sanctions as "unreasonable bullying" for his work defending China's national security.
"The so-called sanctions... are meant to impose pressure and make me hesitate," he told reporters.
"But their unreasonable moves will only reinforce my belief that I have been doing the right thing."
Lee was "disappointed" with YouTube's decision but said his campaign would not be affected, adding that he would start visiting local communities after social distancing rules are relaxed on Thursday.
Parent company Google defended removing the channel, saying it was in compliance with US sanctions that ban American companies and individuals from providing services to targeted officials.
"After review and consistent with these policies, we terminated the Johnlee2022 YouTube channel," a company spokesperson said.
Tam Yiu-chung, a campaign director for Lee as well as Hong Kong's sole representative to China's top lawmaking body, also criticised YouTube's decision.
"They simply said we have violated their relevant policies," Tam said. "We find this completely unreasonable."
But Tam insisted Lee's bid to lead Hong Kong would not be affected.
"They cannot stop us from disseminating the information for our campaign and our candidate to the public," he said.
Lee was among 11 top Hong Kong and Beijing officials to be sanctioned by the US Treasury in 2020 in the wake of China's imposition of a sweeping security law aimed at snuffing out dissent in the financial hub.
Other officials sanctioned include outgoing Hong Kong leader Carrie Lam, former police chiefs Chris Tang and Stephen Lo, as well as Secretary for Justice Teresa Cheng.