the group in September last year, Britain's Defence Secretary Michael Fallon has said.
"This figure is highly approximate, not least given the absence of UK ground troops in a position to observe the effects of strike activity," Fallon said in a written parliamentary statement.
"We do not believe there have been any civilian casualties as a result of UK strike activity."
Britain has regularly conducted attacks on ISIS targets in Iraq as part of U.S.-led air strikes, but does not take part in raids in Syria after Prime Minister David Cameron lost a 2013 parliamentary vote to approve military action against Syrian President Bashar al-Assad.
Cameron is keen to win parliamentary backing to extend raids against Islamic State into Syria, with Fallon saying the current position is illogical.
However, some members of Cameron's Conservative party are opposed to expanding air strikes and newly elected opposition Labour leader Jeremy Corbyn is a veteran anti-war campaigner meaning he could not be certain of winning a vote.
Earlier this month, Cameron said two British nationals who had been fighting for ISIS had been killed by an RAF drone strike in Syria. He justified this move on the grounds of self-defense, saying one of the men had been plotting to carry out attacks on Britain.