The prospect of armed officers opening fire on arsonists during riots only risks inflaming violence, say campaigners.
An official review of police tactics found officers could shoot arsonists as a last resort if they endangered life by attacking businesses attached to people’s homes.
Sir Denis O’Connor, the chief inspector of constabulary, called for a public debate on how much force officers should use to quell disorder similar to that which swept through English cities in August.
Plastic bullets and water cannon may also be considered, he said.
Sir Denis said: “Police have to be able to defend civil order but they need support from the public and others when they do that.”
Half of people surveyed for the review thought police did not use enough force during the riots, while a third thought firearms should have been used against rioters.
A quarter of the 2,000 members of the public surveyed between September 16 and 18 thought police were already using water cannon.
Sir Denis added: “If we don’t raise some of these awkward issues, then we’re not giving people the chance to prepare for a future where we’re slightly more assured as to what will happen.
“Some new rules of engagement are necessary so the police can protect the public in confidence.”
There had been a “long period of peace” where civil order was not top of the agenda, but now it needed to be given priority again, Sir Denis said.
But Shami Chakrabarti, director of human rights campaign group Liberty, said: “How on earth would bullets have quelled and not inflamed this summer’s riots? Didn’t the widespread disorder all begin in Tottenham with a fatal police shooting?”
Jenny Jones, a member of the Metropolitan Police Authority, added: “Endorsing the use of live ammunition is an approval of the tactics of war on London’s streets and implementing such recommendations would be madness.”
Policing Minister Nick Herbert said the report was simply stating the existing law.