"It is little early to make any definite comments on the unfortunate crash of Ukrainian Airlines crash. The aircraft was new and fresh from the check, however, the nature of crash indicates that the pilot encountered problem immediately after takeoff. This usually happens in case of loss of control due to human error or technical malfunction including engine failure," Vardhan said.
According to the expert, debris shows that the "aircraft was carrying a large amount of fuel due to a long flight and fuel tank exploded before or after impact."
"Foreign object damage or sabotage can’t be ruled out at this stage. We have to wait for detailed information for coming to an actual cause of the crash," he added.
The Ukrainian Foreign Ministry's consular service said that no possible causes of the crash could be announced at this stage since the investigation was still underway.
In the wake of the crash, UIA has already indefinitely suspended all international flights to Tehran.
In the morning, Ukraine’s plane crashed near Tehran's Imam Khomeini International Airport. The fire left no survivors among about 180 people who were on board. The carrier, Ukraine International Airlines (UIA), said that the Boeing 737 was built in 2016 and had undergone scheduled maintenance on Monday. It added that a pilot error was unlikely to have caused the crash since all crew members had had enough experience and flight hours.