FILE PHOTO: Renu Begum, sister of teenage British girl Shamima Begum, holds a photo of her sister as she makes an appeal for her to return home at Scotland Yard, in London, Britain February 22, 2015. REUTERS/Laura Lean/Pool/File Photo

LONDON (Reuters) - Decisions to deprive Britons of their citizenship are based on evidence and not taken lightly, Prime Minister Theresa May’s spokesman said on Wednesday.

Britain stripped a teenager who traveled to join Islamic State of her citizenship on security grounds, triggering a row over the ramifications of leaving a mother with a jihadist fighter’s child to fend for herself in a war zone.

“Any decisions to deprive individuals of their citizenship are based on all available evidence and they are not taken lightly,” May’s spokesman said. He declined to comment on the individual case of 19-year-old Shamima Begum.