The Iranian authorities have arrested five suspects in this connection.

Meanwhile, the Saudi consulate has authorized a lawyer to file lawsuit against the hotel, which was closed down temporarily following the incident.

The number of Saudis affected by poisoning rose to 33, seven of them are still in intensive care unit.

The Iranian Food and Drug Authority officials confirmed that the Saudis were poisoned from an unlicensed insecticide that was sprayed in the hotel.

Minister Hashemi said the authorities are continuing intensive investigation into the incident. “The lab tests of samples taken from the victims showed that there was poison in their blood. There is a possibility of deliberate poisoning unless the investigation proved otherwise,” he said.

Abdullah Al-Hamrani, acting Saudi consul general in Iran, said that those admitted in hospital are expected to be discharged on Tuesday. “We have discussed with a lawyer about filing lawsuit against the hotel immediately after the completion of the ongoing investigations,” he said.

A 14-year-old girl and three children aged around three from Al-Qatif governorate died due to chemical poisoning in a Mash’had hotel. A source close to the family said the death cases were due to the leakage of a chemical substance into the room where the Saudis were staying. The chemical substance came through the central air-conditioning ducts.

The source said the family travelled to Mash’had last Friday to spend vacation. The poisoning occurred 48 hours after their arrival in Mash’had.