HONG KONG — Banners supporting independence for Chinese-controlled Hong Kong have appeared on a university campus at the start of classes, rekindling tensions over free speech in the semiautonomous city.

The black banners declaring “Hong Kong Independence” in English and Chinese were put up around the Chinese University of Hong Kong’s campus on Monday.

The school quickly took them down but more were put up a day later, according to local media reports.

One remained strung up over a busy central square on Wednesday. Posters on a nearby wall said, “Fight for our homeland. Fight for Hong Kong independence.”

It’s unclear who was responsible but student leaders have been wrangling with the university administration to keep them up.

University officials say the banners are illegal while the student union says they should be allowed to discuss current issues.

Hong Kong, a former British colony, maintains civil liberties unseen on mainland China including freedom of speech following its 1997 handover, but many residents fear Beijing is tightening its grip.

Some young activists start promoting the once-unthinkable notion of independence from mainland China after massive pro-democracy protests ended without resolution in 2014. There’s almost no chance of success but their ideas have alarmed China’s Communist leaders in Beijing.

Hong Kong’s Beijing-backed government has clamped down on such sentiment, including using the courts to get two newly elected pro-independence lawmakers disqualified from office last year for making improper oaths of office.