ISTANBUL: Angry protesters on Sunday pelted the Istanbul mayor's campaign bus with stones while he was touring Turkey's conservative heartland ahead of next weekend's general election.

Images released by the office of Istanbul's opposition mayor Ekrem Imamoglu showed stones smashing the bus's windows at a campaign stop in the eastern city of Erzurum.

Imamoglu was delivering a speech from the bus's roof when he was forced to go inside for cover and drive off.

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Images on social media showed police using water cannon to disperse a group of people who ran after the bus throwing stones.

Imamoglu called the event a provocation and demanded an explanation from local officials.

Turkish media reports said at least seven people received minor injuries.

The province is controlled by the Islamic-rooted party of President Recep Tayyip Erdogan.

The incident underscored the tensions surrounding next Sunday's parliamentary and presidential ballot.

Imamoglu is campaigning on behalf of secular opposition leader Kemal Kilicdaroglu.

The popular Istanbul mayor has been promised a vice-presidential post should Kilicdaroglu win.

Polls suggest that Kilicdaroglu and Erdogan are locked in a dead heat a week from the vote.