BEIRUT (AP) — Activists say Syrian rebels have captured a government checkpoint on the main road to the airport in the northern city of Aleppo as opposition fighters press their campaign to capture the strategic facility.

The rebels are pushing to seize Aleppo’s civilian airport, and captured a base responsible for protecting it last week. Intense clashes also have raged around the nearby Nairab military air base.

The Britain-based Syrian Observatory for Human Rights reported heavy fighting Monday around Nairab’s fuel station. It said there were several regime casualties and one rebel killed.

The Observatory and the Local Coordination Committees activist group also said government forces were shelling southern neighborhoods of the capital, Damascus. There has been intense fighting in recent weeks in southern and northeastern districts of the capital.