The extent of so-called honour killings in the West Midlands cannot be established because there is no legal definition of what constitutes the crime, senior law officials said yesterday.

According to the Crimes of Community: Honour-based Violence in the UK, a report published yesterday by the Centre for Social Cohesion thinktank, the police and Crown Prosecution Service have reported an average of 10 to 12 UK deaths a year.

But the exact number is not known partly because there is no clear definition of what honour killing involves, the report said. As a result, many organisations believe this figure could be considerably higher.

Last November, the West Midlands CPS was the first in the country to distribute a leaflet dealing with the issue. Printed in five different languages, Love, Honour and Obey aimed to encourage victims or witnesses to come forward with information on how they could receive support.

At the time David Blundell, the chief crown prosecutor for the West Midlands, said: "Some communities talk of honour crimes and forced marriages. There is no such concept in English law.

"If a so-called honour crime has taken place or a forced marriage, then criminal offences will have been committed and the police and the CPS will do everything in their power to ensure successful prosecutions.

"We will protect and support victims during the criminal process. Crime is crime. Victimising your own family is unacceptable in the 21st century."

In yesterday's report, Nazir Afzal, the CPS lead on honour-related violence, said officials involved in tackling crimes of this nature had faced difficulties in prosecuting everyone involved.

He said: "It's easy to prosecute someone if you've got a knife with blood on it and on the murder weapon you've got the perpetrator's DNA - that's easy.

"But we have to go after everybody who's involved. It's always much more difficult to go after a conspiracy than a straightforward criminal act."

In June last year, the CPS piloted a new approach in four "hotspot" areas for honour violence including the county, where a team of 20 prosecutors was based.

Each was trained by a number of different agencies including the police, the Government's forced marriage unit and the independent victims group, the Southall Black Sisters. The Birmingham project was launched five months later.

In the Centre for Social Cohesion report, which gathered information from 80 interviews with women's groups, the CPS said it was essential for teaching young people that honour violence was not acceptable.

Mr Afzal said it was important to educate children about the issue as in spite of the belief only older generations were involved, there was evidence third generation immigrants - born and brought up in the country - had carried out honour-related crimes.

"I used to believe that once the older generation have died, all these practices would just die out. But now you get 21-year-olds who were brought up here saying exactly the same thing.

"I had one guy who said to me, 'a man is like a bar of gold, a woman is like a piece of white silk'.

"He then said that, 'if gold gets dirty you can just wipe it clean, but if a piece of silk gets dirty, you can never get it clean again - and you might as well just throw it away'. "That's a 21-year old speaking. The work now has to be done with the nine and 10-year olds."

Education was needed to tackle causes of honour-based violence at primary and infant school to change attitudes as soon as possible.

"It needs to become part of the curriculum," he said. "It should be part of the citizenship agenda. "Some of the faith schools - particularly in east London have been quite good at this. It doesn't matter if a school is 90 per cent Asian as long as they're getting the right sort of education."