"When I say young, all but four of those 22 were aged 20 or younger," Senior National Coordinator for Counter Terrorism Policing Helen Ball said on BBC One’s Andrew Marr Show.
At least five of the women were between the ages of 15 and 16, Ball said adding that the problem of British girls joining radical Islamists is growing.
"The more everyone involved in travel understands this problem and can be alerted and can be vigilant and can look out for people, the better," she said.
Ball’s statements came shortly after surveillance footage emerged seemingly showing three disappeared British schoolgirls at a bus stop in Turkey.
Last year, 16-year-old twin girls ran away from their home in Manchester and boarded a plane to Turkey, later crossing the border with Syria. Another schoolgirl set to join ISIL was stopped from flying to Turkey in December last year, when her plane was blocked by police on the runway.
A total of 60 British women are believed to have traveled to Syria to join militants, according to UK police.