Harassment is not only a terrifying ordeal for witnesses of crime, but also stops many serious incidents from reaching the courts and justice being served because people are afraid to testify.

The majority of people who either fall victim to or witness a crime respond by contacting the police, and so begins the process of tracking down the culprits and bringing them to justice.

However, in a minority of cases, the perpetrators turn on victims or witnesses and bully them into backing down from reporting the crime.

Their tactics range from verbal and physical threats to full-blown assaults and attacks on property.

It is a terrifying situation and one which can dissuade even the most determined individuals from reporting an incident.

Criminal offence

Victim intimidation is more likely to follow offences of violence and vandalism, according to the British Crime Survey (BCS) 1998.

Women are particularly likely to experience intimidation following a violent offence (26%) - many of these incidents involve domestic violence.

In most cases (85%) the person carrying out witness harassment is the original offender - however it is sometimes the offender's family or friends.

Simon Hughes: Better protection needed

Witness intimidation happens usually in cases where people have witnessed either an act of vandalism, car crime or a serious fight or assault, according to the BCS.

About 75% had been intimidated by the original offender and about 20% were threatened by the perpetrator's family or friends.

Any such intimidation is a criminal offence and punishable under the 1994 Criminal Justice and Public Order Act.

However some, including Liberal Democrat home affairs spokesman Simon Hughes, believe it is not enough of a deterrent.

Death threat

Mr Hughes, who is MP for North Southwark and Bermondsey, knows at first hand the seriousness of witness harassment and intimidation.

A contract was taken out on his life in October 1999, after he successfully persuaded key witnesses to give evidence that helped convict a gang of thugs who had beaten a teenage boy to death in London.

He persuaded witnesses to come forward in the case of 17-year-old Jamie Robe, who was murdered on the Osprey estate, Rotherhithe in August 1997.

The trial of Jamie Robe's killers involved witness protection

The ensuing police investigation and trial cost the taxpayer dearly to ensure justice was carried out.

About 20 people had to be moved away from their homes by the Metropolitan Police's witness protection unit - one of eight nationwide, with powers to provide new homes, new identities, new jobs, and in some cases, new schools for witnesses' children.

Eventually, the witnesses were able to give evidence from behind a screen while wearing balaclavas and boiler suits.

Mr Hughes had a round-the-clock guard on his home and office after the threat was made.

'Swift action'

Of the current situation on witness protection, he told BBC News Online: "It is better than it used to be.

"Witnesses can appear behind a screen and don't have to give their address in court.

"But the thing that has totally failed is giving people assurances they can move.

"I have set up a scheme in Southwark where if there is domestic violence, there is a very speedy system of dealing with the case.

"If someone is a victim of this, they can get swift action with both social services and the police involved."

Mr Hughes is also trying to influence the Criminal Justice Bill.

He said: "I'm proposing that we might get a more common system whereby evidence of prosecution or defence witnesses who feel vulnerable doesn't automatically get passed on to the other side unless the court authorises it and decides it is safe.

"The evidence wouldn't be shown if it wasn't going to be used and the court would decide how the person giving evidence would be protected."

The Criminal Justice Bill would allow some trials to be heard in front of a judge only, if there was a strong suspicion of jury-tampering.