ISTANBUL — Turkish police on Friday detained five suspected IS jihadists in Istanbul accused of planning a “sensational” attack targeting the weekend referendum on expanding President Recep Tayyip Erdogan’s powers.

Police detained the five, including one citizen of Tajikistan, in simultaneous raids on three districts, the state-run Anadolu news agency said.

It said they were acting on intelligence of a planned “sensational” attack on Sunday’s tightly contested referendum. It did not give further details.

Turkish authorities already detained 19 suspected Islamic State (IS) supporters in the Aegean city of Izmir on Tuesday, accused of planning to sabotage voting in the referendum.

In the latest issue of its magazine Al-Naba, IS had called for attacks against polling stations in Turkey.

Turkey has been hit by a series of attacks in the last 18 months blamed on IS and Kurdish militants.

The last major attack claimed by IS was on January 1 when an armed man stormed an Istanbul nightclub and shot 39 people dead during New Year celebrations.