Berlin - The dreams and hopes of the youngsters murdered in one of Germany's worst school shootings were kept alive at a memorial service for the victims in the town of Winnenden on Saturday.

Students of the Albertville Secondary School where the massacre occurred wore black T-shirts with the words "I have dream," written in green - the colour of hope.

School principle Astrid Hahn referred to Martin Luther King's famous speech when she addressed the congregation at the start of the ceremony in the concrete-and-glass church of St Karl Borromaeus (Charles Borromeo).

"We don't want to see these dreams and hopes fade into oblivion," she said. All these dreams can give us the energy and courage to carry on with our lives."

Classmates of the eight teenage girls and one boy gunned down by 17-year-old Tim Kretschmer on March 11 placed a series objects next to the altar as symbols of the dreams and desires of the victims.

Among them was a school report that Hahn said was meant to symbolize the trials that life presents. There were also rings depicting friendship, footprints showing steps towards the future and a party frock expressing the joy of life.

The town of Winnenden is still struggling to come to terms with the killings, which claimed a total of 15 lives before Kretschmer turned his gun on himself after being wounded by police in a shootout 40 kilometres away.

Police still have not established a motive for the crime, although experts have linked it to the teen's addiction to violent computer games, love of guns and mental state - he was reportedly suffering from depression.

Ten days after the bloodbath it was still too early to ask "why?" Bishop Gebhard Fuerst said in his sermon. "Now is the time to shed tears, to lament, to mourn."

His protestant counterpart, Bishop Frank Otfried July, paid his respects to the victims, adding he hoped "the perpetrator of these terrible murders" would find his peace with God.

The pistol used by Kretschmer was stolen from his father, an avid weapons collector who kept 15 guns and 4,600 rounds of ammunition in his home.

In an open letter to Chancellor Angela Merkel and President Horst Koehler, the families of the victims appealed for laws to be tightened so that young people do not get into the possession of such weapons.

"In our pain, in our helplessness and in our anger, we do not wish to remain idle ... (We want) to help so that we will never have another Winnenden."

The message, which appeared in the local newspaper Winnender Zeitung, also called for less violence to be shown on television and a ban on violent computer games.

In a speech delivered following the religious service, a visibly moved Koehler took up the issue, saying that he, too, was in favour of outlawing such games and films containing extensive and graphic depictions of violence.

"Doesn't our common sense tell us the permanent consumption of these products causes harm? I believe this form of 'market development' has to be halted," he said.

It remains to be seen what action, if any, is taken

Some studies have found that video games do not contribute to violence, while others claim to have established a link. (dpa)