China on Tuesday urged its citizens to postpone trips abroad as the country expands a massive effort to contain a viral outbreak that has killed more than 100 people nationwide.

The recommendation to delay non-essential travel was issued “in order to protect the health and safety of Chinese and foreign people”, the National Immigration Administration said in a statement.

“Reducing people’s cross-border movement helps to prevent and control outbreaks,” the agency added.

Authorities had already suspended domestic and overseas Chinese group tours as part of nationwide efforts to combat the coronavirus outbreak, which has infected more than 4,500 people across the country.

Chinese nationals took almost 150 million trips abroad in 2018, the official Xinhua news agency reported in May.

A drastic reduction of trips abroad from China could deal a severe blow to the international tourism industry.

The number of tourists from the country has increased nearly tenfold since 2003, according to a report by research firm Capital Economics.