By Kylie MacLellan and Emma Batha

LONDON (Reuters) - Britain will introduce new laws to combat female genital mutilation (FGM) including making it compulsory for teachers and health workers to report cases, Prime Minister David Cameron said on Tuesday.

The government, hosting a one-day London summit on FGM and forced marriage, also announced 1.4 million pounds (1.4 million pounds) of funding for an prevention programme and said it would enact legislation that would see parents prosecuted if they fail to prevent their daughter undergoing such a practice.

"It's absolutely clear what we are trying to achieve...and that is to outlaw the practices of female genital mutilation and childhood and early forced marriage; to outlaw them everywhere, for everyone, within this generation," Cameron said.

He urged countries to sign up to an international charter, launched at the summit, which calls for the eradication of both practices and said 21 countries had already done so.

FGM, the partial or total removal of external female genitalia, is a tradition practised widely in many African and Muslim countries and often justified as a means of suppressing a woman's sexual desire to prevent "immoral" behaviour.

Around 103,000 women aged between 15 and 49, and another 10,000 girls aged under 15 who have migrated to England and Wales are estimated to have undergone FGM, according to a report on Tuesday from City University London.

Worldwide, more than 130 million girls and women have undergone FGM and more than 700 million women alive today were children when they were married.

Ministers and officials from Pakistan, Somalia, Ethiopia, India, Bangladesh, Burkina Faso, Zambia and others also pledged to step up efforts to tackle both issues.

But UNICEF warned that population growth, particularly in Sub-Saharan Africa, meant the number of FGM victims would soar and there would be no decline in the number of child brides unless global action was dramatically accelerated.

Story continues

Cameron said ending FGM and child marriage was a global challenge on a par with eradicating poverty and tackling diseases.

"We are dealing with a preventable evil. This does not need to happen," he told the summit attended by more than 500 delegates from 50 countries.

Malala Yousafzai, the Pakistani schoolgirl and girl's rights campaigner who was shot in the head by the Taliban in 2012, said getting girls into school was the best way to fight child marriage and FGM.

She told the summit it was wrong to think that Islam was against women's education and empowerment and urged those who thought so to go back to the Koran.

FGM has been a criminal offence in Britain since 1985 but new legislation in 2003 introduced a maximum prison sentence of 14 years. The 2003 act also made it an offence for British citizens to carry out or procure FGM abroad, even in countries where the practice is legal.

(Editing by Catherine Evans)