Major Issam Al-Reis, spokesman for the Free Syrian Army, said rebels had regained areas of Sheikh Miskin in Daraa that government forces entered over the previous two days.
Speaking to Al Arabiya, he said FSA fighters expelled government forces from Brigade 82 after receiving military reinforcements.
US Secretary of State John Kerry meanwhile expressed concern to Russian Foreign Minister Sergey Lavrov about hundreds of civilians killed in what he described as indiscriminate Russian airstrikes in Syria.
The latest information documented by the Syrian Observatory for Human Rights indicated that at least 800 civilians, including around 200 children, had been killed by those strikes over the preceding three months.
The same telephone call discussed the reported killing of Jaysh Al-Islam leader Zahran Alloush in Russian strikes. Kerry expressed regret. A US State Department spokesman said Washington certainly had reservations about the group’s rhetoric and tactics but recognized that Alloush had been prepared to participate in UN-sponsored peace negotiations.
Assad’s forces had announced on Wednesday that they had gained control deep inside Sheikh Miskin in southern Daraa province.
The FSA attributed the advance to intensive Russian air support, with more than 100 strikes over two days. Iranian, Iraqi, and Lebanese Hezbollah militias also entered the city from several directions, amid reports of disagreements among FSA factions.