At least four Pakistani soldiers have been killed after militants attacked an army checkpoint close to the Afghan border, officials say.

Security officials also say at least 10 militants were killed in the ensuing battle; that number has not been independently confirmed.

A spokesman for the Pakistani Taliban said they carried out the assault in the Mohmand tribal area.

Cross-border attacks on Pakistani forces has been a source of tension.

Pakistan has previously complained about Pakistani Taliban fighters using Afghanistan as a base to stage such attacks.

But Afghanistan and the US say the Afghan Taliban operate within Pakistan's borders to plan attacks on Western forces in Afghanistan, something Pakistan denies.

Nevertheless, analysts say Mohmand is one of several districts in Pakistan's volatile tribal areas where militants have carved out strongholds.

Last summer, the army stepped up raids on militant hideouts in the district.