The National Security and Defense Council (NSDC) of Ukraine is considering three "classified theories" about why Ukraine International Airlines (UIA) flight PS752 was downed by Iran early in January 2020.

"There are three classified theories we are working on. Including who was interested in this and who else took part," NSDC Secretary Oleksiy Danilov said in an interview for the Ukrainian media outlet

Read alsoIran says Ukrainian plane's black box damaged – media

He said the work was on to gain access to the black box recorders of UIA's Boeing plane.

"Technical processes are now underway along with the approval of procedures. We are in touch with Iran on a daily basis. We are working," Danilov added.

As UNIAN reported earlier, Kyiv-bound UIA flight PS752 crashed shortly after takeoff from Tehran's Imam Khomeini International Airport in the early hours of January 8. It was carrying 167 passengers and nine crew members on board. Two passengers and the crew members were Ukrainians. There were also 82 citizens of Iran, 63 citizens of Canada, 10 citizens of Sweden, four citizens of Afghanistan, three citizens of Germany and the United Kingdom each. There were no survivors.

On January 11, Iranian President Hassan Rouhani officially admitted that the Ukrainian airliner had been shot down by accident as a result of a "human error" and that those responsible would be held accountable.

On February 2, intercepted communications between Tehran Airport's air traffic control tower and the second pilot of Iran's Aseman Airlines flight at the time of the crash of flight PS752 were released by TSN.Tyzhden. Tehran blamed the Ukrainian authorities for leaking what it described as confidential evidence, and said it would no longer share investigation materials with Ukraine.

On February 14, the Iranian Foreign Minister said Iran did not plan to hand the black boxes over but it would not decrypt their data without the participation of the parties concerned.