The warning came as Afusat Saliu, 31, was taken into custody by UK Border Agency staff yesterday, and has been told she will be flown back to the African country tonight.
Ms Saliu fled to the UK in 2011 while she was heavily pregnant after her stepmother threatened to subject her daughter Bassy, now four, to female genital mutilation (FGM). Her second daughter, Rashidat, two, was born in London.
Ms Saliu, herself a victim of FGM, has said she fears her children will be cut and she will be forced to marry a man against her will if she returns to her native country.
More than 120,000 people have signed a petition calling for the Home Office to halt her deportation, but despite this border officials seized her and her two daughters and plan to put her on to a plane to Lagos tonight at 10pm, campaigners have claimed.
Anj Handa, a friend, said: “There is a risk of forced FGM on her two children if they are made to go back to Nigeria. Afusat is a victim of that herself. It is too late for her, but we have a four year-old and a two-year-old and they are the ‘right age’ for cutting from her family’s point of view.”
Since moving to Leeds three years ago Ms Saliu has converted to Christianity, and friends fear she will be targeted by Islamic militants Boko Haram if she is deported.
It is understood Ms Saliu was taken into custody with her two children at 2pm and detained at a holding centre in Sheffield before being moved on to Cedars, a family immigration centre in Sussex.
Her solicitors at BP Legal have launched a judicial review in a last-ditch attempt to keep her in Britain.
And they have accused Home Office officials of ignoring their own guidelines by ordering her deportation before the review is heard.
Figures have suggested as many as 66,000 women in England and Wales have undergone FGM and 23,000 girls under the age of 15 are at risk of it.
A Home Office spokesman said they do not comment on individual cases. Ms Saliu’s petition can be viewed at http://www.change.org.