RAF air strikes in Iraq and Syria killed and injured an estimated 4,315 enemies with just one civilian fatality, according to estimated figures released by the Ministry of Defence (MOD).
The figures, covering a period from September 2014 to January this year, were released following a Freedom of Information (FOI) request by the campaign group Action on Armed Violence (AOAV).
They suggest that of the 4,315 combatants targeted, 4,013 were reported to have been killed (93%) while 302 (7%) survived with injuries.
In total, 75% of those estimated to have been killed or injured were in Iraq and 25% in Syria.
In February, the US military said at least 1,257 civilians had died as a result of 33,921 US-led coalition airstrikes between August 2014 and January 2019.
The Royal Australian Air Force (RAAF) also said it was "possible" that as many as 18 civilians were unintentionally killed during airstrikes over Iraq.
In response to the figures, the Defence Secretary said it showed the level of "professionalism" and "skill" the RAF has.
The Defence Secretary said he is 'proud' of the RAF
"That professionalism is right at the core in terms of everything we do and that's how they've been able to minimise any form of civilian casualties and I think we should be all very proud of that," Gavin Williamson told Forces News.
"The reason that we've been able to be very open and report to parliament as to where we are and what we're doing and any possible impact is that amount of time we take in terms of not just the planning, but the analysis post-strike to ensure we've done everything we can to minimise any form of impact on anyone else other than the targets that are a threat to our country."
AOAV executive director Iain Overton greeted the figures with scepticism, saying: "The RAF's claim of a ratio of one civilian casualty against 4,315 enemies must be a world record in modern conflict.
"Yet few conflict experts believe this to be true."
"The MOD notes in the FOI release that 'information concerning enemy killed and wounded in action is based on the best available post-strike analysis'.
"This information, however, is only given as an estimate as the UK is not in a position to visit air strike sites inside Syria and verify the facts.
"To them, it is clear that far more needs to be done by the UK to improve transparency surrounding civilian casualties from airstrikes. Its coalition partner, the US, has committed to such, so why not the UK?"
It is understood the MOD has carried out more than 1,700 strikes during the campaign, reporting only the one civilian casualty during an operation on 26 March last year.
The individual died after crossing into the strike area on a motorbike moments before the blast, the MOD said.
Three IS fighters, who were driving in the Syrian Euphrates valley at the time, were also killed by the precision Hellfire missile.
Of all enemies estimated killed and wounded by the RAF, 37% were by Typhoons, 31% by Tornados and 32% by Reapers.
An MOD spokeswoman said: "After every British airstrike we conduct detailed battle damage assessment, which thoroughly examines the outcome of the strike against its target, be it Daesh fighters, weapons, or bases.
"This assessment also looks very carefully at whether or not there has been any civilian casualty or damage to civilian infrastructure."