The NSPCC children's charity has referred 34 potential cases of female genital mutilation to the Metropolitan police as a result of calls to an anonymous helpline launched less than three months ago to help tackle a crime understood to affect more than 70 women and girls a month in the UK.

John Cameron, head of the helpline, said the 93 calls received so far had come from members of the communities that practise female genital mutilation, which is a criminal offence carrying a sentence of up to 14 years in prison in the UK, as well as education and healthcare professionals seeking advice. The calls showed the "need for a single anonymous point of contact for information", he said.

The details emerged as police and prosecutors called for members of these communities as well as education and health professionals to come forward and report so-called "cutters". Female genital mutilation has been illegal in the UK since 1985, yet there have been no prosecutions to date. Three years ago, in an effort to stamp out a practice estimated to affect a total of 66,000 women and girls in England and Wales, the crime was extended to anyone who took a girl overseas to be cut, or helped anyone else do so.

Keith Niven, detective chief superintendent responsible for child abuse and rape in the Metropolitan police service, said those working in education, health and social services all needed to help spot children at risk. "If people have genuinely held cultural beliefs [that FGM is acceptable], their views and opinions need to be changed. This is a harmful practice."

A roundtable meeting called by the director of public prosecutions, Keir Starmer, on Thursday heard from government ministers, police officers, heathcare professionals, social services and other interested parties keen to stamp out the abuse. Calling for greater public awareness and a more co-ordinated response, Starmer said he saw signs of progress. "It's not a question of whether there will be a prosecution but when," he said in an interview with the Guardian. "It's now only a question of time."

He welcomed the "considerable progress" that had been made in the past 12 months. "A year ago we had a situation where people were barely aware of what was going on," he said. There were no cases referred to the CPS before 2010.

Since starting to record cases of possible FGM in 2009, the Met has received 186 referrals. "That doesn't reflect the nature and extent of this issue," admitted Niven. "My ambition is that we get more referrals from education, health professionals and social services … The police are at the end of this process. It's all gone wrong when it gets to us."

Evidence of how few cases get referred to the police came from Avon and Somerset health service where one midwife recorded 117 cases in one nine-month period.

A health professional at the roundtable raised concerns about confidentiality but Starmer said: "I understand the concern about confidentiality but we need to be clear here that FGM is a serious crime, an offence that carries a penalty of 14 years."

To calls for a co-ordinated response from schools when teachers spot signs of potential abuse, Martin Howarth, head of children's rights and wellbeing at the Department for Education, indicated that his department was unlikely to produce national guidelines for schools to follow in suspected cases of FGM. "We are reducing the amount of central guidance that goes out to schools. There are tensions in this."

Asked why prosecution was so important, Starmer, who leaves the CPS next month, said: "It will send a very powerful message about the fact that FGM is unacceptable."

Anyone who is worried that a child is at risk of or has been a victim of FGM can contact the NSPCC helpline 0800 028 3550 for information and support.