HONG KONG — The Hong Kong government barred a young pro-democracy activist on Saturday from an upcoming election over her party’s political platform that it said violates electoral laws, in the latest move by the semiautonomous Chinese city to squelch dissent.

An official statement said the nomination of a female candidate, who was not identified, was ruled invalid.

Agnes Chow, a 21-year-old member of democracy activist Joshua Wong’s Demosisto party, confirmed it was her.

Chow is the latest to fall victim to the Beijing-backed government’s tightening restrictions on opposition candidates, including a new wave of young activists who emerged from huge 2014 “Umbrella Movement” demonstrations against China’s plans to restrict elections for Hong Kong’s top leader.

She was planning to stand in a March by-election, but the government said the returning officer decided she couldn’t be a candidate because of Demosisto’s platform, which advocates “self-determination” or independence for Hong Kong in violation of the city’s Basic Law constitution.

Chow intended to replace fellow Demosisto member Nathan Law, who was among six opposition lawmakers removed from office after the government won a legal battle over their swearing-in ceremonies. Wong was prevented from running because he was given a prison sentence in a case related to the 2014 protests, in which all three played prominent roles as student leaders.

“If a person advocates or promotes self-determination or independence by any means, he or she cannot possibly uphold the Basic Law or fulfil his or her duties as a legislator,” the government said.

Chow told reporters the disqualification was “political screening.”

“Hong Kong is not even ruled by rule of law, it’s just ruled by the Beijing government,” Chow said. “The decision to disqualify my candidacy is no less than a declaration to the city that our political rights are handicapped.”