More than 50 pro-democracy politicians and campaigners have been arrested in early morning raids in Hong Kong, in an unprecedented crackdown by authorities on opposition in the region. The activists were reportedly held under the national security law over accusations they “subverted state power” by holding primaries and saying they intended to win a majority of seats in the Hong Kong election. The sweeping arrests on Wednesday morning came without warning, and shocked observers. It is the largest single mass arrest of people under the national security law (NSL), and appeared to relate to just a singular event: the holding of democratic votes. Political parties associated with those arrested said the move by police appeared to be related to unofficial primaries held by the pan-democrats last year, ahead of the Hong Kong election. Campaigners had been aiming for 35 seats – a majority in the legislative council. The election was ultimately delayed by Hong Kong’s leader, Carrie Lam, for a year purportedly because of the pandemic. “Being arrested for sedition for taking part in democracy 35+,” tweeted Dr Kwok Ka Ki, one of four legislators disqualified in November, who was detained on Wednesday morning. The Facebook page of jailed activist Joshua Wong, said his home was also raided on Wednesday morning. Among those named as arrested were former lawmakers Helena Wong, Lam Cheuk-ting, Chu Hoi-dick, and Leung Kwok-Hung, as well as co-organisers of the polls – legal scholar Benny Tai and pollster Robert Chung, whose office was raided just days prior. Maya Wang, senior China researcher at Human Rights Watch, said the mass arrests removed “the remaining veneer of democracy in the city”. “Beijing once again has failed to learn from its mistakes in Hong Kong: that repression generates resistance, and that millions of Hong Kong people will persist in their struggle for their right to vote and run for office in a democratically elected government.” UK-based Hong Kong Watch accused Beijing of “once again undermining Hong Kong’s democracy & breaching its obligations under the Sino-British Joint Declaration”. “The international community must respond with Magnitsky sanctions and other punitive measures demonstrating that an attack on democracy has consequences.” At the time of the primaries the Hong Kong government claimed it had received complaints that the poll might have “interfered with and manipulated” the election, and that by pledging to win a majority of seats in order to block government bills candidates and campaigners had potentially violated the NSL. The primary polls, while not a formal part of Hong Kong’s election process, drew an estimated 600,000 people out to vote for democracy candidates in what was seen as a litmus test of the public’s response to government crackdowns, and an act of protest. But Beijing’s top representatives in Hong Kong labelled the primaries “illegal” and accused organisers of colluding with foreign powers in a “serious provocation” of Hong Kong’s electoral system. “The goal of organiser Benny Tai and the opposition camp is to seize the ruling power of Hong Kong and ... carry out a Hong Kong version of ‘colour revolution’,” said a spokesman for the Liaison Office, whose chief is also in charge of implementing the national security laws. After the polls closed Tai predicted as many as 45 seats could be won by pro-democracy candidates, but he was wary of backlash from those in power. “Everyone must be mentally prepared.” The Beijing-designed law was imposed in June last year, and criminalised secession, subversion, terrorism and collusion with foreign forces, including benign acts of protest. Until Wednesday around 35 people had been arrested under the law, and four charged, including media mogul Jimmy Lai. Prosecutors have fought to ensure none are released on bail, suggesting anyone charged from Wednesday’s raids will likely be detained.