Reuters - U.S. Treasury Secretary Steven Mnuchin said on Friday the department will grant sanction waivers to allow Americans or any one else to participate in the investigation of Wednesday�s crash of an Ukrainian International Boeing 737-800 airliner in Iran that killed 176 people.

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

Boeing said on Friday it was working with the Federal Aviation Administration and National Transportation Safety Board �on the necessary applications and approvals from OFAC for the appropriate export licenses.�

The NTSB said late on Thursday it had agreed to be an accredited representative to the investigation of the crash at Iran�s invitation.

�The Treasury will issue waivers for anybody, whether it�s Americans or others that can help facilitate the investigation,� Mnuchin said at a White House news conference.

U.S. Secretary of State Mike Pompeo said on Friday that it was �likely that plane was shot down by an Iranian missile.�

Pompeo said after a thorough probe is completed, he is confident the United States and the rest of the world will have an appropriate response.

Reuters and other media reported on Thursday that U.S. officials reached that assessment based on a review of satellite data that showed two Iranian missile launches shortly before the plane crashed. Iran denies that the plane was brought down by its missiles.

Because of U.S. sanctions law, the NTSB has previously opted not to participate in other crashes of U.S. certified airplanes in Iran. Under international law, the country where a plane was certified has a right to be involved in the probe.

The NTSB did not immediately say if it had sought licenses from Treasury. NTSB said on Thursday it �continues to monitor the situation surrounding the crash and evaluate its level of participation in the investigation.�

Iran said on Friday it wanted to download black box recordings itself from the Ukrainian airliner that crashed. Iran also said it could take one or two months to extract information from the voice and flight data recorders, and could ask Russia, Canada, France or Ukraine if it needed help.

The Transportation Safety Board of Canada said it was making arrangements to tour the site after an Iranian invitation. U.S. Transportation Secretary Elaine Chao spoke to her Canadian counterpart, Transport Minister Marc Garneau, about the crash probe, a U.S. official said.

Sixty-three Canadians were among those killed in the crash.

Reporting by David Shepardson Editing by Chizu Nomiyama, Richard Chang and Bill Berkrot