Johnson made the provocative remarks in a side meeting at the Conservative Party conference in Manchester on Tuesday.
“They literally have a brilliant vision to turn Sirte, with the help of the municipality of Sirte, to turn it into the next Dubai. The only thing they’ve got to do is clear the dead bodies away and then they’ll be there,” he said.
His remarks drew laughter from some activists from Prime Minister Theresa May’s party, but then the chair of the event changed the subject by saying, “Next question.”
Johnson’s gaffe has provoked strong backlash, with some describing his comments as unacceptable and some others calling for his resignation.
“For Boris Johnson to treat those deaths as a joke — a mere inconvenience before UK business people can turn the city into a beach resort — is unbelievably crass, callous and cruel,” said the shadow foreign secretary, Emily Thornberry.
Backbench Conservative lawmaker Heidi Allen along with Anna Soubry, a former Tory cabinet minister, also called on May to “sack” Johnson.
Allen’s cabinet colleagues Damian Green and Sarah Wollaston joined her in criticizing Johnson.
Green told Sky News that “everyone, including Boris, needs to be careful in their use of language,” while Wollaston told a BBC Radio channel that “demeaning jokes about real people murdered in Libya would be crass even from a standup; appalled to hear this from our foreign secretary.”
Johnson, in response, not only did not apologize but attacked his critics on Twitter, saying, “Shame people with no knowledge or understanding of Libya want to play politics with the appallingly dangerous reality in Sirte.”
Damian Green, the first secretary of state, defended Jonson, but said he should have been more careful in choosing his words.
He said that “the bodies he was referring to are often Daesh fighters who have been booby-trapped.”
However, Jeremy Hunt, the health secretary, said he could not defend Johnson’s views, noting, “Boris is Boris and that was very unfortunate language. I don’t want to defend that.”
Johnson’s political career has been dominated by blunt comments and personal controversy.
Sirte, the major stronghold of Daesh outside Iraq and Syria, fell to the Takfiri terrorists in February 2015. The full recapture of the city would be a major boost to the unity government, which has come to office through support from the United Nations.
Daesh has been taking advantage of the chaos embroiling Libya since the NATO-backed overthrow and death of longtime ruler Muammar Gaddafi in 2011.