The US National Transportation Safety Board said Thursday it will join the probe into the Ukrainian Boeing airliner which went down in Iran.

A rescue worker searches the scene where an Ukrainian plane crashed in Shahedshahr, southwest of the capital Tehran, Iran, Wednesday, Jan. 8, 2020. (Photo: AP)

In a statement posted on its Twitter account, the agency said it had "received formal notification" from Iran of the crash which occurred on Wednesday.

The plane, a US-made Boeing 737, went down minutes after takeoff from Tehran, and shortly after Iran had fired missiles at military bases in Iraq housing US troops.

"The NTSB has designated an accredited representative to the investigation of the crash," said the US agency which probes transport accidents.

"The NTSB continues to monitor the situation surrounding the crash and evaluate its level of participation in the investigation," which will be led by Iran, the statement said.

"As with any investigation in which the NTSB is involved, the agency will not speculate about the cause of the crash."