Police, tracker dogs and special forensic teams pressed on with the search for two young girls who disappeared a week ago today as officials said they would resume questioning a convicted sex offender who has been charged with kidnapping the children.
Jacques Leonard, police commissioner in the city of Liege, said police were focusing their searches on a vast abandoned citadel complex on the outskirts of the city, which includes a large forested area.
"It is a deserted place and there are many possibilities to hide people here," Mr Leonard told VRT television.
Police and volunteers have searched parts of the city as well as the Meuse River, which runs through the city centre, after stepsisters Nathalie Mahy (10), and Stacy Lemmens (7) disappeared during a street party last weekend.
Their disappearance has shocked Belgium, 10 years after a kidnap and murder spree by paedophile killer Marc Dutroux.
Police have named Abdallah Aid Oud as top suspect in the case, and said he was to undergo further questioning today.
Investigators have to present magistrates evidence linking Aid Oud to the case next week, or will have to release him from custody, officials said.
Mr Oud (39) who denies any involvement in the case, has twice been convicted of sex attacks on young girls and was released in December after serving a four-year sentence, authorities said.
Police on Wednesday charged him with kidnapping of minors and unlawful detention. He had turned himself in after authorities released his name and photo to the public.
Mr Oud was the boyfriend of a waitress in a cafe where the missing girls spent part of Friday night with relatives. Police say he was in the vicinity shortly before they disappeared at around 1:30am last Saturday.
Justice Minister Laurette Onkelinx met with the family of the missing girls on Friday promising to provide all necessary means to find them.
The case has generated widespread concern in Belgium, drawing parallels with the kidnap a decade ago of two 8-year-olds by Dutroux.
The two were found dead more than a year later in a crime that shocked the country and led to sweeping reforms of the police. Dutroux is serving a life sentence for the murders. AP