* Rebels try to cement control of Aleppo supply line
* Battle to hold strategic town of Maarat al-Nuaman
Rebels attacked a Syrian army base near the main northern highway on Thursday to try to consolidate their control over the supply line to Aleppo, days after capturing a strategic town in the area, opposition activists said.
Rebels used at least one tank seized from the army, as well as rocket-propelled grenades and mortar bombs, to hit the Wadi al-Deif base, three kilometres (2 miles) east of the town of Maarat al-Nuaman, which they captured this week, they said.
"The rebels have been attacking Wadi al-Deif since overnight but the army is still shelling Maarat al-Nuaman from it. The city continues to also be hit by warplanes," said Mohammad Kanaan, an opposition activist in the area.
There were no immediate reports of casualties. Reports from Syria are difficult to verify because Syrian authorities have banned most independent media since the outbreak of the revolt against President Bashar al-Assad in March last year.
At least 30 rebels and dozens of loyalist forces were killed on Wednesday in a battle south of Maarat al-Nuaman, where opposition sources said rebels had halted a Syrian army push to retake the town, which is situated on the main highway to Turkey, 280 kilometres (173 miles) north of Damascus.
The centre of the town, located between the desert and the mountains, boasts fortress-like security and intelligence compounds.
Opposition sources said the fall of Maarat al-Nuaman has weakened the army's supply lines to Aleppo, Syria's business hub where urban warfare has been raging for two months.
Turkey has been massing troops along its 900 km (560 mile)long-border in the past week after gunfire and shells from northern Syria hit Turkish territory, prompting it to respond in kind.