'I cannot begin to imagine what went through Boris Johnson and Michael Gove’s minds.'
Zaghari-Ratcliffe was jailed for five years by Iran in September on allegations of spying and attempting to topple the Iranian regime. Her family insist she was in the country on holiday.
Johnson has faced demands he resign after he suggested she was “training journalists” in the country.
Zaghari-Ratcliffe was then summoned back to court and threatened with further charges.
Gove, the environment secretary, deepened the crisis on Sunday after he said did not know why Zaghari-Ratcliffe was in Iran.
Morgan, the chair of the Treasury committee, said today: “I cannot begin to imagine what went through Boris Johnson, and I’m afraid to say, Michael Gove’s minds.
“She was in the country visiting her parents with her young daughter, that’s it, end of story.”
Conservative MP Anna Soubry has already called for Johnson to be fired for “screwing up from the day he was appointed”.
Richard Ratcliffe, Zaghari-Ratcliffe’s husband, has said his wife had “expressed anger” at the foreign secretary over the “shambles” her case has become - but he did not believe Johnson should be forced to quit.
Ratcliffe says his wife is now on the edge of a nervous breakdown. He has urged Johnson to take him on his forthcoming diplomatic mission to Tehran amid growing fears over her health.
Asked about the case as he attended a summit in Brussels today, Johnson said: “On Iran, and consular cases generally, they are all very sensitive. And I think the key thing to understand is that we are working very, very hard, and intensively, and impartially on all those cases.”