The Prime Minister feels Labour MP Austin Mitchell was "quite wrong" to liken Pfizer to "rapists" in a Twitter post, his official spokesman has told reporters.
Asked if David Cameron thought Mr Mitchell should be disciplined by his party, the spokesman said, "He does think this is something for the Labour Party."
Mr Mitchell's original tweet also suggested Mr Cameron "dare not stop Pfizer because he dare not offend the US in any way".
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The chancellor now faces the prospect of forming a minority government or calling for a snap election.
The 73-year-old said a return is unlikely "given the politicised atmosphere that seems to have afflicted our set."
Chancellor Philip Hammond said the UK will make a financial proposal to the EU in the next three-and-a-half weeks.