Several people have been injured by a blast in Istanbul, BBC News said citing Turkish media.

The blast, caused by a bomb, targeted a police bus in the central district of Vezneciler, reports say. Several ambulances have been sent to the area.

Violence in Turkey has escalated recently as a result of tensions with Kurdish separatists and the conflict in neighbouring Syria.

Unverified pictures posted on social media showed shops with their front windows shattered.

The explosion happened during the morning rush hour, near the city's historic Bayezit Square neighbourhood, a major tourist attraction.