HONG KONG –

A member of the pro-independence Hong Kong National Party has been disqualified from running in September’s Legislative Council elections after he declined to sign a controversial new form saying the city is an “inalienable” part of China.

Chan Ho-tin received an email from the Electoral Affairs Commission on Saturday which said his application to join the election had been "invalidated," fueling speculation that others who hold pro-independence views also could be disqualified.

"The National Party is honored to become the first party to be banned from joining a democratic election by the government due to political difference," the party wrote on its Facebook page.

The requirement that candidates pledge that the former British colony is part of China, and that advocating independence could make them ineligible to stand for election, is the latest in a series of issues that have raised concern about what many people in Hong Kong see as mainland China's increasing control.

Hong Kong returned to Chinese rule in 1997 under a "one country, two systems" formula meant to guarantee the financial hub's considerable freedoms and separate laws.

But China's refusal to allow unfettered democracy in next year's election for the city's leader triggered prodemocracy protests in 2014, and spurred worries about the city's future.

A series of issues since then has compounded those fears.

The government issued a statement saying it agreed to and supported the decision to disqualify Chan.

The activist is one of a number of pro-independence candidates who refused to sign the recently introduced additional declaration form.

Previously, candidates only needed to pledge to uphold Hong Kong laws.

A Hong Kong court declined to rule on Wednesday on a challenge filed by activist politicians to the new rule.

About 100 people joined a rally on Saturday night to support Chan.