Syrian rebels pushed towards two military airports in the northern province of Aleppo on Saturday, a day after capturing a similar strategic military base, activists told dpa.
"Heavy fighting is taking place between rebels and troops manning Al-Ming military airport in Aleppo's countryside, resulting in many casualties in government forces ranks," said Abu Omar al-Halabi, a commander in the Free Syrian Army (FSA).
He added that rebels were also targeting Aleppo's Nairib military camp.
On Friday, rebel fighters captured the Tfatanaz northern military base, which had been used by the government to bomb opposition strongholds in northern areas of the country.
Meanwhile, Russia called on Saturday for the launch of a political transition process in Syria, as Russian Deputy Foreign Minister Mikhail Bogdanov met with Syrian opposition members in Geneva, the Interfax news agency reported.
Bogdanov met with UN-Arab League special envoy Lakhdar Brahimi and US Deputy Secretary of State William Burns on Friday.
Moscow said it welcomes continuing consultations on Syria, although Brahimi has said he does not expect a political solution to end the 22-month Syrian conflict.
The Syrian conflict has claimed the lives of more than 60,000 people, according to UN estimates.