Suicide attacker kills 20, wounds several people in Damascus.
Security forces chased three suicide bombers in cars through Damascus, stopping two but failing to intercept a third who killed at least 20 people when he detonated his explosives.
Officials said the bombers had been prevented from reaching their intended targets, otherwise the casualty toll would have been higher.
In a letter to the UN secretary general and the head of the security council, the foreign ministry said the blast that killed 20 people in the Bab Touma area near the Old City had also wounded dozens of women and children.
State media said the bomber had been spotted and pursued by the security forces and set off the bomb after he had been encircled in the area.
It was the first such bombing in the Syrian capital since a series of jihadist suicide attacks in March.
Damascus was hit by two separate, multiple suicide bomb attacks in March, one of them claimed by Isil and the other by the Islamist insurgent alliance Tahrir al-Sham.
Damascus has enjoyed relative security in recent years even as the six-year-long civil war has raged on in nearby areas.
Syria’s minister of local administration Hussein Makhlouf said the response marked a “major success in foiling a plot” to cause mass casualties.
Footage broadcast by state TV from the blast that caused the fatalities showed roads scattered with debris, several badly damaged cars, and another one that had been turned into a pile of twisted metal.
Other footage showed what appeared to be the remains of a person and badly damaged vehicles outside a mosque in the Baytara traffic circle near the Old City.
On March 15, two suicide bomb attacks in Damascus killed several dozen people, most of them at the Palace of Justice courthouse near the Old City.
Isil claimed responsibility for that attack.
On March 11, a double suicide attack in the capital killed scores of people, most of them Iraqi Shi’ite pilgrims.
That attack was claimed by the Tahrir al-Sham alliance of Islamist insurgents, which is spearheaded by a jihadist group formerly known as the Nusra Front.
Syrian government forces, which have defeated rebel fighters in several suburbs of Damascus over the last year, are currently battling insurgents in the Jobar and Ain Tarma areas on the capital’s eastern outskirts.
A rebel group accused the army of using chlorine gas in the fighting on Saturday. The army denied the claim as fabrications.