The BBC's Bob Sinkinson: "The groups hope to get missing people to re-establish contact with their families"

Concern for families suffering the trauma of a missing relative sparked the appeal, which was backed by the Salvation Army, Red Cross and the National Missing Persons Helpline (NMPH).

The groups support the families, who suffer "great distress" when their loved ones go missing. The NMPH helps reunite them, operating a "Message Home" service for people who have left home but want a message to be passed on.

Janet Newman, co-founder of the NMPH, said: "The helpline would like to take this day to encourage people to keep in touch with their loved ones to try and alleviate the distress - just let your family know you are safe and well."

About 250,000 people are reported missing in the UK each year. Most return home within 72 hours, but there are still about 20,000 unresolved cases on the helpline's register.

43,000 missing people are under 18

The main causes are abuse, debt, domestic arguments, illness, stress and drink and drug problems.

This is the first time that the support groups have united with the police in their effort to raise awareness of the issue of missing people.They are also keen to highlight the help available to families trying to find their loved ones.

A vote of support for the appeal was also given by Home Office minister Paul Boateng. "The absence of a family member for whatever reason is an extremely traumatic experience," he said.

"In the UK and around the world thousands of families at any one time suffer from anxiety and distress because a loved one is missing."

Ms Newman said the crisis in Kosovo and the harrowing stories of the refugees fleeing their homeland were a reminder of the emotional distress caused when someone goes missing.

But dealing with missing people is not new; The Salvation Army first established a service to help trace missing adult members in 1885.

Men go missing most