AMMAN (Reuters) - The Syrian army has taken full control of a small airbase in the eastern Aleppo countryside that had been held by Islamic State, helped by heavy aerial bombing by Russian and Syrian airforces, pro-state media and an army source said on Saturday.

The al-Jarrah airport is located in the hardline militants’ remaining enclave in eastern Aleppo countryside, a region where they have mostly lost control to competing forces ranging from the Syrian army, U.S.-backed Kurdish-led forces to Turkey-backed Free Syrian Army (FSA) rebels.

The airport was briefly stormed by the army’s elite forces last March, but the militants repelled that attack on the base they had held since 2014.

A rebel source with an Islamist faction operating in the area said a convoy of army vehicles had been hit by the militants. The convoy had been ferrying reinforcements to the area on a strategic supply route south of Khanaser, located some 50 km (30 miles) southeast of Aleppo city.

The Islamic State militants are waging fierce battles with the Syrian army and Iranian-backed militias supporting it in the area. As the militants lose more territory, they have been resorting to more hit-and-run attacks that deploy suicide bombers from vast rural areas where they have taken shelter.

Russian and Syrian jets have also intensified their attacks on the town of Maskaneh, the last main town in the region west of the Euphrates River in eastern Aleppo countryside, former residents in touch with relatives said.

Dozens of civilians have been killed since last week in the aerial bombing of the remaining villages and towns in the area still in the control of the militants, the UK-based Syrian Observatory for Human Rights said.

Separately Amaq, a news outlet affiliated to the militants, said U.S. coalition strikes on the villages of Shanina and al Rashid farm in the northern countryside of Raqqa killed at least seven civilians and injured 45 people.

U.S.-backed fighters have been waging a campaign to isolate and ultimately capture the city of Raqqa since November.

With air strikes and special ground forces from the U.S.-led coalition, the Syrian Democratic Forces (SDF), has been advancing on Raqqa city from the north, east and west.

Activists and former residents, as well as the U.K.-based monitor, have documented in the last month dozens of civilian deaths during air strikes in Islamic State-held areas that the SDF was pushing toward. Thousands of local Arab villagers have also been displaced.