The Metropolitan Police chief said a campaign launched to identify possible victims of female genital mutilation (FGM) "warns" people of the law.
Sir Bernard Hogan-Howe said: "They have an option to stop - the fact they bought a ticket to me is irrelevant.
"They should not be committing a serious attack on a child and they should not be breaking the law."
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Colder but clear this evening
Two teenagers found dead at the foot of a sheer drop at Huntcliff have been named as 17-year-olds Alex Yeoman and Harry Watson.
Violet Grace Youens died in hospital a day after she was struck in a suspected hit and run as she walked with her grandmother in Merseyside.