US President Donald Trump has pilloried an envoy who testified in the impeachment inquiry, claiming she refused to hang his photo in the American embassy in Ukraine.
Mr. Trump made the claim on Fox News' morning show.
The president did not offer details about the matter.
Former ambassador Marie Yovanovitch testified last week that she was fired over false claims by people with questionable motives.
She was one of 12 witnesses to testify over the last fortnight in the impeachment inquiry, which may seek to remove the president from office for alleged corruption.
It was not the first time the Republican president has attacked Ms Yovanovitch.
He lambasted her in a tweet while she was testifying last Friday - a move that Democrats argued amounted to witness intimidation.