Afghan President Ashraf Ghani has declared a national day of mourning after scores of soldiers were killed at a military base by Taliban fighters dressed as fellow soldiers.

One official says at least 140 soldiers were killed and many others wounded, while other officials say the toll is likely to be even higher.

As many as 10 Taliban fighters in army uniforms and driving military vehicles, drove into the base and opened fire on mostly unarmed soldiers eating and leaving a mosque after Friday prayers.