A suicide bomber has killed 16 people - including four Nato soldiers - in an attack on the outskirts of Bagram air base in north-eastern Afghanistan.

Ten civilians and two police officers were also reportedly killed in the attack on a clinic near the largest US base in the country.

The attack comes amid a mounting crisis over the presidential election result.

Supporters of losing candidate Abdullah Abdullah say he will create a "parallel government" if his rival is elected.

US Secretary of State John Kerry has warned that a failure to accept the result could harm security and aid.

Source: BBC