DUBAI - Saudi Arabia summoned Iran’s ambassador on Tuesday after four Saudis died from poisoning in the northeast Iranian city of Mashhad, Saudi foreign ministry spokesman Osama Naqli said in a statement published on the state news agency.

A group of 33 pilgrims from Saudi Arabia’s Shi’ite Muslim minority was exposed to poison on Sunday while staying at a Mashhad hotel, state news agency IRNA reported on Monday. Another Iranian news agency quoted an official as saying the poisoning appeared to be accidental, blaming poor cleaning standards at the hotel.

Four children died, while another 28 were hospitalised after the incident. Iranian authorities said they arrested five members of hotel staff. Saudi Arabia’s foreign ministry called on Iran to “swiftly take the necessary investigations requiredto provide protection.