The General Staff of Iran's Armed Forces on Wednesday released the second report on the causes of a helicopter crash that resulted in the deaths of Iranian President Ebrahim Raisi and his entourage, according to Mehr News Agency.

"The occurrence of an explosion as a result of an act of sabotage during the flight and moments before the helicopter crashed into the mountain is ruled out," the report stated.

It also said that "no signs of an act of electronic warfare were detected on the helicopter."

Additionally, investigators carefully examined the vast majority of the documents related to the maintenance of the helicopter and found no issue that could have played a role in the accident, it added.

Investigators also ruled out any disruption in the communication system or frequency interference with the helicopter. They revealed that during the flight and up to 69 seconds before the crash, contact with the aircraft had been maintained on the specified frequencies.

The General Staff issued its preliminary report on the incident on May 24. It said the investigation will continue until the main cause of the crash is determined and the results will be made public.

Read more: Iran releases its first investigation report on President Raisi's helicopter crash