By Lin Taylor

LONDON, Dec 17 (Thomson Reuters Foundation) — As many families prepare to holiday abroad during the festive season, British charities on Monday warned that girls taken overseas could be at risk of female genital mutilation.

Known as FGM, female genital mutilation is a ritual that usually involves the partial or total removal of the external genitalia, including the clitoris. Some girls bleed to death or die from infections.

Cutting affects an estimated 200 million girls worldwide and is a rite of passage in many societies, often with the aim of promoting chastity, with the highest prevalence in Africa and parts of the Middle East.

Take Action: Help Global Citizen End Female Genital Mutilation

An estimated 137,000 women and girls in England and Wales have undergone FGM. Many cases go unnoticed because they had happened at a young age and abroad, campaigners say.

Campaigners say teachers should look out for warning signs, such as when a child is taken abroad for a long time to a country where there is a high prevalence of FGM.

"The best way of preventing the practice is by working with girls and their families ... and training professionals like teachers and social workers to spot girls at risk of FGM," said Leethen Bartholomew, head of Britain's National FGM Centre.

Some warning signs that a girl might have been cut include difficulty walking or sitting down, spending a long time in the toilet or becoming withdrawn, said the Centre, run by children's charity Barnardo's and the Local Government Association.

FGM has been a criminal offence in Britain since 1985. Legislation in 2003 made it illegal for British citizens to carry out or procure FGM abroad, even in countries where it is legal.

In 2015, it became mandatory for health professionals, social workers and teachers in Britain to report known cases of FGM to police.

The practice mostly affects immigrant communities from various countries including Somalia, Sierra Leone, Eritrea, Sudan, Nigeria and Egypt.

Read More: FGM Happens in the UK, But Is Obscured by a Very British Silence

British-based charity Forward, which supports FGM survivors from African communities, said though teachers have a crucial role to play, they should not stigmatise certain communities.

"While teachers need to be alert at all times about safeguarding children in their care, we also need to ensure that some communities are not unduly targeted and stigmatised," said Naana Otoo-Oyortey, executive director of FORWARD.

"Ending FGM requires multiple entry points (and) enabling families and communities to be proactive in ending the practice of FGM is ultimately the most effective channel," she said in emailed comments to the Thomson Reuters Foundation.

Britain in November pledged 50 million pounds ($63 million)to combat female genital mutilation in Africa. ($1 = 0.7957 pounds)

(Reporting by Lin Taylor @linnytayls, Editing by Claire Cozens. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's and LGBT+ rights, human trafficking and slavery, property rights, social innovation, resilience and climate change. Visit http://news.trust.org to see more stories)