Iran accidentally shot down the Ukrainian passenger plane that crashed near the capital Tehran on Tuesday killing more than 170 people, according to US officials.

The crash late on Tuesday came just a few hours after Iran launched a ballistic missile attack against Iraqi military bases housing US troops.

The missile attack came amid a confrontation with Washington over the US drone strike that killed an Iranian general last week.

CBS is now reporting US intelligence said a satellite detected infrared "blips" of two missile launches, followed by another blip of an explosion.

Downing Street said it was looking into “very concerning” reports about the crash, with Prime Minister Boris Johnson using a phone call with Ukrainian President Volodymyr Zelenskyy to call for a “full, credible and transparent investigation” into what happened.

President Donald Trump suggested he believes Iran was responsible and would not directly lay the blame on Iran, but dismissed their claims that it was a mechanical issue – and denied any US responsibility.

“Somebody could have made a mistake on the other side,” Mr Trump said, noting the plane was flying in a “pretty rough neighbourhood”.

“Some people say it was mechanical,” Mr Trump added.

“I personally don’t think that’s even a question.”