A photo taken early Monday morning shows people surrounding a burned car after an accident that caused an explosion which killed 16 in downtown Cairo. The accident was caused by a speeding car heading in the opposite direction and collided with three other cars, the health ministry said. Photo: VCG

The Chinese Embassy in Cairo issued a security reminder on Tuesday, warning Chinese citizens in Egypt to be more aware of security risks after a car explosion killed at least 20 people in downtown Cairo.

A car packed with explosives blew up outside Cairo's main cancer hospital on Monday, the interior ministry said.

The huge blast was caused by a speeding car packed with explosives, Egyptian officials said Monday, as the president decried a "terrorist incident."

In its security reminder, the embassy said that Chinese citizens in Egypt should raise their awareness of security risks, pay close attention to changes in the security situation and avoid visiting densely populated areas or sensitive religious sites.

"Tourists should obey the unified command and arrangements of tour guides, avoid going out without authorization or alone under any circumstance, and strictly avoid the Sinai Peninsula area except Sharm El-Sheikh and the Bahariya region of Giza Province," the statement said.

Egypt has been under a state of emergency in the past month. On July 11, the Egyptian parliament extended it for three months beginning July 25.

That marked the ninth time the state of emergency has been extended since April 10, 2017, when President Abdel Fattah al-Sisi declared it for the first time following deadly bombings that targeted two churches in Alexandria and Tanta the day before, killing 44 people.