BEIJING — China is instituting new controls in a northeastern province where several new cases of COVID-19 are believed to have originated.

China on Monday reported five new cases of local transmission, all in Liaoning province or believed to be linked to its cases.

Checkpoints were set up at toll stations, airports and railway stations in three cities in Liaoning and travelers must have proof of a recent negative virus test, according to state media reports Monday. Mass testing was ordered in part of Yingkou, a port city with shipping connections to more than 40 countries.

China had largely stamped out domestic transmission of the coronavirus through restrictions on the public, contact tracing, mass testing and, increasingly, vaccinations. Health officials suspect the domestic cases may have spread through contacts with an imported case.

China has reported 90,872 confirmed cases of COVID-19 and 4,636 deaths since the virus was detected in Wuhan in late 2019.