Campus security has been beefed up across the country with more police officers and security guards stationed in and around schools on Tuesday, the first day of classes following the three-day May Day holiday.

Parents escort their children through the gate of a primary school in Shapingba district, Chongqing, on Monday. Local police officers have been dispatched to guard schools in the city.

The tightened security measures follow a series of violent attacks against school or kindergarten children in recent weeks.

In Southwest China's Chongqing municipality, the local public security bureau set up police teams at all kindergartens, primary and middle schools, local media reported on Tuesday.

Police were told that they could "shoot on site" any suspect who is violently offending or hurting students on campus or in surrounding areas, the Chongqing Evening News reported.

People who live near schools or who have possible mental problems will be better monitored. Those who are discontent with society and have threatened to retaliate will also be closely watched, the report said.

Similar measures were being taken nationwide on Tuesday.

In Guangzhou, capital city of South China's Guangdong province, at least one police car will be sent daily patrol to every school in downtown Yuexiu district, Guangzhou Daily reported on Tuesday.

The city authorities ordered schools to check and register every visitor, prohibiting unauthorized people from entering the campus, and preventing knives or flammable, explosive and toxic materials from being carried into schools.