Seven Hong Kong pro-democracy local councillors were unseated on Wednesday after the government declared their loyalty oaths were invalid, part of an ongoing campaign to purge the city of anyone deemed unpatriotic.

District councils are the only political office in Hong Kong where almost all members are directly elected by residents, with 452 out of 479 seats filled by public ballot.

They deal with bread-and-butter local issues such as bus routes, trash collection and playgrounds.

But they have also become a symbol of residents' urge for a greater say in how their city is run, and pro-democracy candidates won a landslide two years ago.

China has since responded with a crackdown on dissent as well as an overhaul of the city's political system, under which anyone standing for office must be vetted for patriotism.

On Wednesday the government announced that seven councillors who took new loyalty oaths last week were not deemed patriots and were therefore unseated. 

Among the seven were Clarisse Yeung and Michael Pang, both of whom have been charged under a sweeping national security law that Beijing imposed on Hong Kong last year to crush recent democracy protests.

Most councillors refused to take the oath -- 268 simply quit before the new rules came in.