Angry protesters Sunday pelted the Istanbul mayor's campaign bus with stones while he was in eastern Erzurum province ahead of the May 14 elections in Türkiye.

Images released by the office of Ekrem Imamoğlu showed stones smashing the bus' windows.

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

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

Imamoğlu called the incident a "provocation" and demanded an explanation from local officials. Reports said at least seven people received minor injuries.

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

Imamoğlu is campaigning on behalf of secular opposition leader Kemal Kılıçdaroğlu. The popular Istanbul mayor has been promised a vice-presidential post should Kılıçdaroğlu win. Polls suggest that Kılıçdaroğlu and President Recep Tayyip Erdoğan are locked in a dead heat a week from the vote.

Speaking on the incident, Interior Minister Süleyman Soylu said on Ülke TV that the Republican People's Party (CHP) asked for permission from the provincial election board to "visit craftspeople" and not to "hold a rally."

Erzurum Mayor Mehmet Sekmen, on the other hand, claimed that the group of 150-200 people was from within the CHP.

"The designation of the meeting areas, issuing the meeting permits, and all kinds of election-related management are at the disposal of the Provincial Election Board. Upon this incident, I asked the Provincial Election Board, ‘Is there such an application?’ and they said that ‘There is no written application of the CHP Provincial Chairmanship to hold a rally,'" Sekmen explained.

Officials of the ruling Justice and Development Party (AK Party) said that these provocations were made to shadow the major Istanbul rally of Erdoğan at Atatürk Airport, which drew 1.7 million people and showed ongoing support to the incumbent.

Following the Erzurum rally, Imamoğlu landed at Sabiha Gökçen Airport and held a speech, accusing the police of not intervening while he was attacked in the eastern province earlier in the day.

"These stones were not thrown at Ekrem Imamoğlu. These stones were thrown at our brotherhood. They were thrown at the values, belief and unity of the nation," he said.

Imamoğlu added that he would file a complaint against Sekmen and Erzurum Governor Okay Memiş.