The funeral of Nathalie Mahy, who was raped before being killed, was attended by only close friends at the request of her father.

The funeral of her step-sister Stacy Lemmens will take place tomorrow in Sainte-Foy church, where she was baptised, and will be broadcast on state television. The girls will be buried in identical white coffins.

Both girls disappeared from a street party in the rundown SaintLeonard district of Liege at around 1.30am on 10 June. Their bodies were found after an 18-day search, in a storm drain about half a mile from the bar from which they disappeared. Police had already searched the area before but had failed to find the corpses because of dense undergrowth.

Last Wednesday they went back with heavier equipment and made the first of their two discoveries at about 11am. Just after 4pm the second body, that of Nathalie, was removed from the railway line in a blacked-out van and taken for examination.

Autopsies showed that both girls died of suffocation as a result of being strangled and Nathalie's body also showed signs of rape.

Told of the discovery, Christiane Granziero, Stacy's mother, was taken ill and had to be admitted to hospital. Both girls' parents had been clinging to hope that the girls would be found alive and photographs of the girls had been distributed around the continent.

Police said the girls' bodies had been in the drain for several days and were in the same state of decomposition, suggesting that they died soon after they went missing.

A team of 20 forensic scientists examined the bodies, searching for proof to link the murders with the investigators' only suspect, Abdullah Aid Oud, a 38-year-old convicted child rapist.

Aid Oud has been charged with the girls' kidnapping and has been held by police since handing himself in on 13 June, when he was identified publicly as a suspect. He was seen at the Aux Armuriers bar where the two girls were last seen alive and is the boyfriend of one of the waitresses there.

But Aid Oud denies any involvement in their disappearance, and the public prosecutor for Liege said the discoveries had "not produced new elements linked to the person in custody". The prosecutor also said there were no other suspects.

Aid Oud's lawyer has pressed for his release, arguing that there is no proof against him. But a court ruled that there was sufficient circumstantial evidence to keep him jailed.

This includes witnesses placing him near the spot from which the children disappeared, the fact that he then shaved his head in an apparent effort to alter his appearance, that scratches were found on his body and that he has a record of child-sex crimes.

If examination of the bodies links Aid Oud to the murders, the Belgian judicial authorities will face questions about why he was released from prison last December, despite his record.

The fate of Stacy and Nathalie stirred memories of the crimes of the notorious child-killer and convicted paedophile Marc Dutroux.

Dutroux snatched two eight-yearolds, Julie Lejeune and Melissa Russo, from a Liege street in 1995.

He held them captive for months and sexually abused them before allowing them to starve to death in the basement of his house in Marcinelle while he served a prison sentence for a minor offence.

It took almost 10 years to bring Dutroux to trial, during which time he sexually abused a further four girls. The case exposed major deficiencies in the police investigation and prompted a police shake-up and a change of government.

This time, Belgian police are under increasing pressure to close the case quickly to end speculation that a paedophile ring remains in operation.

Mourners have been laying flowers and candles near the spot where the bodies of Nathalie and Stacy were discovered. A book of condolences, covered in photographs and white roses, was opened at Liege city hall.

Psychologists were provided to help the friends of the two girls to come to terms with their deaths and the girls' classmates were given a day off school to help them deal with the shock.

"Our city, our community is suffering enormously, " said Liege mayor Willy Demeyer.

"The city is extremely sad but also angry about the unjust violence to which these two small girls were subjected."

Earlier in the week, Belgium's prime minister Guy Verhofstadt, said that "priority will be given to uncovering the culprit, or culprits, in this terrible double murder".

"I can assure you that none of them will get away with this. In all our hearts there is a feeling of repugnance, of sorrow and powerlessness. We cannot comprehend what motivates these people, " he said.

Elio Di Rupo, premier of the French-speaking Wallonia region, said the discovery marked "a new black day for Belgium" and Crown Prince Philippe, heir to the Belgian throne, scaled back a trade visit to Moscow as a sign of respect. "As parents ourselves we want to express our feelings with the parents, " he said.

In light of the killings, the European Union's top justice official urged member states to step up their fight against paedophilia and child pornography.

Franco Frattini, EU justice and home affairs commissioner, said the European Commission is to adopt a European charter on children's rights next week, to increase the level of protection.

"I think the whole of Europe has to voice its outrage and horror at the murder of the two children here in Belgium, and we can only hope that the police and judicial inquiries under way will quickly bring the guilty person or persons to justice, " he said.