Syria's president has threatened that regime forces could storm the north of the country to recapture areas out of its control, as a major offensive looms in the south.

Syria's president has threatened that regime forces could storm the north of the country to recapture areas out of its control, as a major offensive looms in the south.

Bashar al-Assad made the remarks in an interview aired on Sunday with Russian state-run NTV television channel.

"We're going to attack them and take control by force, which is not our favorable way, but it's the only way to gain control of the country," Assad said, responding to question about the "occupation" of northern Syria.

"We adopted two ways: the first one and the main one was the reconciliation," he added.

Much of Syria's north is controlled by a US-backed alliance dominated by the Kurdish People's Protection Units (YPG) and Turkey-backed rebel forces.

The northern city of Manbij is held by the YPG, but Ankara considers them "terrorists" and has threatened to attack the city.

The comments come as Russia-backed regime forces been preparing for weeks for an offensive to retake Syria's south, a strategic zone that borders both Jordan and the Israeli-occupied Golan Heights.

On Saturday, Russian warplanes began bombing the rebel-held zone for the first time since summer 2017.

During the sit-down interview, Assad also said he was undecided on running for another presidential term.

"There are two factors here: the first one is my wish, and it proceeds from the second factor - the will of the Syrian people," he said.

Rebels have long demanded that Assad must step down before any peace deal can be reached.