Members of China's paramilitary People's Armed Police have been seen marching and practicing crowd-control tactics at a sports complex across from Hong Kong, in what some have interpreted as a threat against pro-democracy protesters.
Hong Kong's government has refused to talk with demonstrators who have protested since early June to demand expanded political rights and the scrapping of legislation that could have seen criminal suspects sent to China.
Vehicles belonging to the paramilitary People's Armed Police were arrayed Friday in Shenzhen, a city just across from Hong Kong.
Hong Kong police officers said Thursday they weren't aware of plans for Chinese forces to join efforts to quell the demonstrations.
The protests have been marked by increasing violence and shut down the Hong Kong airport earlier this week.