Belgium's Justice Minister, Stefaan de Clerck, has given the team permission to hire specialist equipment used in the Cromwell Street inquiry.
Commenting on claims that missing teenagers An Marchal, 19, and Eefje Lambrecks, 17, could be in Germany or the Czech Republic, Mr Bourlet said: "We are following the trails, but at the moment these are just rumours. We are trying to remain optimistic that An and Eefje are still alive."
The investigation into thescandal continued at a string of addresses across Belgium yesterday, but there was still no sign of the two teenagers, who vanished from Ostend a year ago.
The rescue last week of two girls from a cellar where they had been imprisoned had raised hopes of finding the girls. Marc Dutroux and Michel Lelievre, the two men at the centre of the paedophile investigation, have admitted kidnapping them.
But despite speculation that the teenagers may have been sold into prostitution abroad, detectives have not yet made any formal approaches to foreign police for help.
Books of condolence for Julie Lejeune and Melissa Russo, both aged eight, have been opened in many towns and cities across Belgium. Their bodies were discovered at the weekend in Sars-la-Buissiere, near Charleroi, buried in the garden of Dutroux, a convicted rapist and paedophile whose child- sex crimes were discovered last week. The girls starved to death earlier this year while 39-year-old Dutroux was in prison. They will be buried on Thursday.
In the Charleroi suburb of Marcinel, where Laetitia Delhez, 14, and Sabine Dardenne, 12, were found alive in a sound-proof cellar and where Julie and Melissa are believed to have died, people continue to sign the national petition calling for tough penalties for paedophiles.
Dutroux, his second wife Michelle Martin, and associates Lelievre and Jean-Michel Nihoul all face charges in connection with the kidnapping and abuse of Laetitia and Sabine. There are fears they may also be involved in the disappearance of another six children.Reuse content