Iran said on Wednesday that it will not hand over black box recordings recovered from the fallen Boeing 737-800 that crashed shortly after take off in Ukraine at the Tehran airport.

According to BBC, head of Iran's Civil Aviation Organization (CAO), Ali Abedzadeh, said the black box will not be given to "the manufacturer and the Americans," based on a published comment by Iran's Mehr news agency.

Abedzadeh reportedly said reiterated that Iran's aviation group will take over the investigations of the crash alongside Ukrainian authorities although it is unclear which of the two countries will look into the flight data recorder and cockpit voice recorder retrieved from the crash site.

While global aviation regulations state that Iran should be leading the investigations, most of the time, in such cases, manufacturers of fallen jets are involved as well. However, analysts noted that Tehran's decision came amid tensions between the United States and Iran.

When Ukraine International Airlines flight PS752 crashed in Iran on Wednesday, the Ukrainian embassy in Tehran initially said the crash was triggered by an engine failure. However, there were no official statements given yet regarding the main cause of the tragic crash that took the lives of 176 people on board.

Ukraine's President Volodymyr Zelensky said there should be "unchecked theories" on the matter until official results from the investigation emerge. On the other hand, some local media outlets blamed technical issues or the crash.

Canada has expressed its desire to help with the investigations, especially considering that there were 63 Canadians who passed away due to the tragedy. There were also 11 Ukrainians and 82 Iranians on board.

Of the deceased, fifteen were children, and there were also Germans, Britons, and Swedes who were killed, as revealed by Ukrainian Foreign Minister Vadym Prystaiko.

Commenting on the crash, former U.S. Department of Transportation inspector general and currently a pilot, Mary Schiavo, argued that "there was no way for Iran to know it was engine failure," USA Today reported.

Schiavo examined photos of the Ukrainian Boeing 737-800 wreckage and she noted that no evidence pointed to potential engine problems. Based on her analysis, Schiavo said the something blew the plane "out of the air."

For former U.S. National Transportation Safety Board (NTSB) chairman Jim Hall, the main concern should be on whether or not there will be an independent investigation on the crash, considering that Tehran refuses to involve the neither U.S. nor Boeing.

The Guardian reported that in recent years, several Boeing 737-800 jets have experienced safety issues. Some were grounded due to cracks in the fuselage as well as the wing area.

The fallen plane is also recognized as the most popular aircraft on flight globally. As of February 2019, over 4,900 of the said jets have been delivered to various carriers around the world.