BEIRUT — Syria’s rebels stepped up attacks on strategic sites including a sprawling military complex in the country’s north on Friday, while reports emerged that President Bashar Assad’s forces continued to fire Scud missiles at rebel areas.
Russian President Vladimir Putin told European leaders that Russia does not seek to protect Assad but that only a negotiated solution can end the conflict — an outcome that looks unlikely as rebels make gains across the country.
While few observers expect Syria’s 21-month-old conflict to end soon, most say steady rebel advances appear to be tipping the balance in favor of those fighting to topple Assad’s regime.
Regime foes reported rebel attacks on strategic government sites in northern Syria on Friday, showing rebel efforts to cut government supply lines, free up roads and seize arms from government bases.
Near the northern city of Aleppo, rebels clashed with government forces at a sprawling military complex by the town of Al-Safira, activists said.
An activist in the town said the complex contains military factories, a scientific research center that produces chemical weapons as well as an air defense and an artillery base.
Rebels seized the artillery base earlier this week and have been trying to seize the air defense base, said Hussein, who gave only his first name for fear of retribution.
The town’s proximity to the facilities has cost it dearly, he said. Government airstrikes often target civilian areas, and more than two-thirds of the town’s residents have fled, fearing the regime will use chemical weapons.
‘‘We are scared that they will be blown up or that the regime will use them in revenge on the town,’’ he added.
Bilal Saab, head of the Institute for Near East and Gulf Military Analysis, confirmed that the Al-Safira complex houses a chemical weapons production facility but said it is unclear if such weapons have been stored there ready for use, or if rebels would be able to use them.
The Britain-based Syrian Observatory for Human Rights said seven rebels were killed in clashes in the area on Friday. It said nearly two dozen more died in a government airstrike earlier this week after they captured a military warehouse.
Activists also said rebels had launched attacks on a number of military targets near the central city of Hama.
Activist Mousab Alhamadee said rebels had seized five army posts in the last two days near the town of Morek, which straddles the country’s primary north-south highway north of Hama. Only one army tank battalion remains in the town’s immediate area, he said, giving the area’s rebels much more freedom to move.
‘‘The regime is losing a complete geographic area,’’ he said.
‘We are scared that they will be blown up or that the regime will use them in revenge on the town.’
Syria’s conflict started with political protests in March 2011.
The government says the rebels are terrorists backed by foreign powers that seek to destroy the country. It does not give death tolls, although anti-regime activists say more than 40,000 have been killed.
International diplomacy has failed to slow the conflict.
On Friday, Russian President Vladimir Putin said that his country does not seek to preserve Assad’s rule but wants a ‘‘democratic regime in Syria based on the expression of people’s will’’ — an outcome he said can only come through negotiations.