Syrian warplanes hit rebel positions near a contested military air base in the north on Tuesday, June 18, activists said, while President Bashar Assad's forces nearby pressed ahead with an offensive against opposition fighters in the country's largest city Aleppo, according to The Associated Press.

The Britain-based Syrian Observatory for Human Rights said that fighter jets struck near the Kweiras air base near the Turkish border early Tuesday. Opposition forces fighting to oust Assad's regime for more than two years have been trying for months to take Kweiras and two other military air bases nearby.

The Observatory, which relies on a network of informants inside Syria, also reported heavy clashes in Aleppo, the country's commercial hub.

There were no reports of casualties in either the strikes or the fighting.