BEIRUT (Reuters) - Syrian government forces backed by heavy Russian air strikes recaptured a town seized by Islamic State near the road used by the army to access Aleppo, though the route remains cut, the Syrian Observatory for Human Rights said on Thursday.

The town of Khanaser is located some 50 km (30 miles) southeast of Aleppo city. Islamic State captured it two days ago, the Observatory said. Syrian state media said the army had "restored security and stability" to Khanaser.

A news agency close to Islamic State militants, Amaq, said its fighters had to pull out of the town after the Syrian army and Shi'ite militias who had sent large reinforcements entered the town aided by intensive Russian aerial bombing.

It also said the highway was still closed.

The ultra-hardline militants were now waging ferocious battles with the army on the northern edge of the town near the villages of Rasm al-Nafal and Bourg al-Zarour, Amaq said.

The militants had also looted 12 tanks and a large cache of munitions since the start of the offensive, mainly from an arms depot in the area, the report said.

The government has been forced to use the Khanaser road to reach Aleppo because insurgents control the main highway to the city further west.

Rebels battling government offensives in the Aleppo area have said the Islamic State attack in Khanaser appeared to have eased the pressure on their frontlines with the government.

Islamic State is not included in a U.S.-Russian plan aimed at bringing about a halt to the fighting in Syria that is due to take effect on Saturday.

(Writing by Tom Perry; Editing by Alison Williams)