Protests are planned starting Friday at Hong Kong’s airport, which could disrupt travel to and from the city. And the city has been roiled by daily demonstrations that have led the police to fire tear gas, rubber bullets and bean bag rounds at protesters.

The Hong Kong government said Thursday that the city remained a welcoming place for visitors and had a long tradition of peaceful protests.

“However, in recent weeks, some violent protesters have blocked roadways, vandalized property and confronted police after the end of some processions,” the government said in a written statement. “The impact of these illegal confrontations is confined to a limited area near the procession routes, and is not widespread.”

On Wednesday, the top Chinese official overseeing Hong Kong affairs said that the city was experiencing its worst crisis since the former British colony returned to China in 1997. The official, Zhang Xiaoming, the director of the Hong Kong and Macau Affairs Office, said the turmoil in Hong Kong “has been going on for 60 days straight, getting bigger and bigger,” and added that violence had been intensifying.

The advisory urged travelers to the city to “avoid the areas of the demonstrations,” “keep a low profile” and “exercise caution if unexpectedly in the vicinity of large gatherings or protests.”