Anxious Singapore shoppers formed long lines at grocery stores Saturday and cleared the shelves of essential items, after the city-state raised its alert level over China's coronavirus outbreak. Since emerging late last year, the virus has killed over 700 people and infected more than 34,000 in China, and spread to many other countries.

Singapore, which has reported 33 cases, raised its alert level Friday to "orange" - the same as during the deadly 2003 SARS outbreak, indicating the virus is severe and passes easily between people.

The announcement triggered panic in the city-state of 5.7 million starting late Friday, with shoppers - many wearing masks - rushing to stock up on items including rice, noodles and toilet paper.

Pictures circulating on social media showed empty shelves in some stores, carts filled with goods and long lines at counters, which continued into Saturday.

"I'm afraid that if they further raise the alert level, we will not be able to go out," a 50-year-old housewife, who did not want to be named, told AFP after leaving a grocery store.

The highest level on Singapore's four-point scale for dealing with disease outbreaks is "red", one above "orange".

There were, however, ample stocks of other items such as fruit, meat, fish and alcohol.

The government urged calm, with Trade Minister Chan Chun Sing saying there was no need to rush out to buy crucial supplies. "There is no risk of us running a shortage of essential food or household items," he wrote on Facebook.

Singapore raised its alert level amid a growing number of virus cases in citizens with no recent travel history to mainland China and no known links to previous infections. Hong Kong has also been hit by a wave of panic-buying in recent days as it seeks to battle the virus, with supermarket shelves frequently emptied of crucial goods.