°®Âþµº

The United Kingdom is set to revoke the citizenship of a British teenager who left her home in London four years ago to join the Islamic State group, a family lawyer said on Tuesday.

A copy of the Home Office letter sent to Shamima Begum's mother informing her of the decision was obtained by broadcaster ITV and shows the government department asking her to "ensure the Home Secretary's decision is brought to" Shamima Begum's attention.

Attorney Tasnime Akunjee tweeted on Tuesday that the family is "very disappointed with the Home Office's intention to have an order made depriving Shamima of her citizenship."

He said the family is "considering all legal avenues to challenge this decision."

Begum ran away with two friends in 2015, when she was 15, and travelled to Syria.

Now 19, she says she has given birth to a baby and wants to come home.

The case has reignited a debate in the UK about how to deal with citizens who joined IS but now want to return.

British authorities estimate around 900 Britons travelled to Syria and Iraq to join the conflict, of whom around 300-400 have since returned - and 40 have been prosecuted.

As of last month, around 200 were believed to still be alive and in the region.