Lavrov told reporters the weapons had been re-located from several locations and were secure for the time being.
"The Syrian government has concentrated the stockpiles in one or two centers, unlike the past when they were scattered across the country," Lavrov said.
Syrian President Bashar Assad was still relatively secure in the capital Damascus and had no plans to leave the war-torn country, Lavrov said on a flight back to Moscow from a European Union summit in Belgium.
Russia has been a longtime ally of Assad and Lavrov maintained Syria's poison gases would be safer in the government's hands than they would if rebel groups, including Islamist militants, got control of them, the BBC reported.
Fighting persisted Saturday between rebels and Assad loyalists. The Syrian Network for Human Rights said in a written statement 23 people had been killed during the day.
Nearly half of the casualties were reported in the Damascus area, and one died after being tortured. No details were provided.