A taskforce to examine "honour killings" was launched last year

They aim to set up a pan-European unit to combat the killings and crack down on related issues such as trafficking.

Police are re-opening murder files related to families of Turkish, Middle Eastern, Asian, Arabic and Eastern European origin over the past 10 years.

Many victims of "honour killings" are women involved in relationships their family felt brought dishonour on them.

I think we've been unaware, we've been ignorant of the crimes going on Andy Baker UK police commander Q&A: Honour killings explained

Experts say such killings are on the rise in Europe, but as the issue remains largely hidden from public view, exact numbers are unknown.

As the conference continues at The Hague, a Swedish representative is expected to highlight the case of a young woman called Fadime.

A 26-year-old Kurd, Fadime was shot dead two years ago near Stockholm, allegedly by her father because of her relationship with a Swedish man.

The murder triggered calls for urgent action to protect young immigrants who fall out with their families.

Contract killers

In England and Wales police are reinvestigating more than 100 murders they suspect could be honour killings.

There has to be real commitment to bring to justice those who perpetrate such heinous crimes Dr Asia Gill Scotland Yard adviser

Detectives from London's Metropolitan police are examining murder files going back 10 years - 52 in the capital and 65 in other parts of England and Wales.

Many of the female victims were from South Asian communities.

Police say some of the murders were carried out by contract killers hired by the families.

They also believe that so-called "bounty hunters" were involved - people, including women, who make a business out of tracking down victims.

The Metropolitan police also say that two women a week are reporting to them in circumstances in which they may be in danger.

Last September the UK police announced new research into the culture surrounding honour killings.

The undertaking followed the conviction of Abdalla Yones, a Kurdish Muslim, for the murder of his 16-year-old daughter Heshu after she formed a relationship with a man of whom he disapproved.

Fighting loopholes

At the time, Commander Andy Baker, head of the Metropolitan Police's Serious Crime Directorate and the chair of the new strategic taskforce, said the force needed to understand why the killings took place.

He said police had been "unaware" and "ignorant" of crimes that were going on.

The police are concerned about the high proportion of honour killings which end in convictions for manslaughter rather than murder, the BBC's crime correspondent Neil Bennett reports from The Hague.

The police have urged the government to investigate possible loopholes in the law - and the move has been widely supported by crime experts.