Hong Kong's democrats have won their battle to veto a Beijing-backed electoral reform package, but they now face an increasingly organized campaign by pro-Chinese government movements in the longer war over the democratic future of the former British colony.

The tense hours before the vote sparked protests by dozens of pro-Beijing groups outside the Legislative Council — a push that diplomats, politicians and academics believe highlights an intensified effort by China to exert control over the Asian financial hub.

That effort is run through the United Front Work Department, a branch of the Communist Party's Central Committee with a mission to spread China's reach by gaining control and influence over a range of groups not affiliated with the party, sources with ties to Beijing say.