WASHINGTON, Jan 21 (Reuters) -

General Electric Co has received a license from the U.S. Treasury Department to help in the investigation of a Ukrainian passenger plane accidentally shot down by Iranian forces, a GE spokesman told Reuters on Tuesday.

Treasury Secretary Steven Mnuchin said earlier this month that the department would grant sanction waivers to allow Americans or anyone else to participate in the investigation of the Jan. 8 crash that killed all 176 people onboard.

GE co-owns with France's Safran SA the French-U.S. firm CFM that made the plane's engines.

The U.S.-built Boeing 737 flown by Ukraine International Airlines was shot down in error by Iranian forces during a period of tit-for-tat military strikes that included the killing by the United States of a senior Iranian general on Jan. 3.

Under U.S. sanctions law, the Treasury's Office of Foreign Assets Control (OFAC) must grant approval for U.S. investigators to participate in the probe of the crash and potentially travel to Iran.

Iran has made requests for equipment from U.S. and French authorities so it can download information from the black boxes on the downed plane, but Tehran has not received a positive response, Iran's Civil Aviation Organization said.

Tehran has said it would read the flight data and voice recorders inside Iran, after giving mixed signals about whether it would send the black boxes abroad, as requested by Canada, Ukraine and other nations with citizens aboard the flight.

Iran and Canada, which lost 57 of the 176 people killed in the crash, have been at odds over who should analyze the downed plane's black boxes.