Masked Islamic State militants attacked a border post on the Tajik-Uzbek border overnight, triggering a gun battle that killed 15 of the militants, a guard and a policeman, Tajik authorities said on Wednesday.

There was no immediate announcement from the militant group, which has claimed responsibility for a series of assaults in Tajikistan in recent months.

Five of the gunmen were captured after the attack on the Tajik side of the border, 50 km (30 miles) southwest of the capital Dushanbe, Tajikistan's National Security Committee said.

It released a photograph showing the badly burned bodies of three men in black military-style outfits, lying on the ground next to a wrecked car.