Islamabad, whose air force primarily operates Chinese-made jets and U.S. F-16s, has previously denied that India downed any Pakistani aircraft during the fighting.

Pakistan has claimed that it shot down six Indian aircraft during the clashes, including a French-made Rafale fighter. India has acknowledged some losses but denied losing six aircraft.

Air force chief says S-400 air defence systems took down most of the Pakistani planes; Pakistan rejects statement.

India shot down five Pakistani fighter jets and one other military aircraft during clashes in May, India's air force chief said on Saturday, the first such statement by the country months after its worst military conflict in decades with its neighbour.