He added that officers could "work there only one hour and during this hour they try, one team after the other, to gather everything available in this living space".
Mr Fritzl also reportedly told his victims they would be gassed if anything happened to him.
Technicians are trying to establish if this was more than a threat.
Work in the cellar is expected to take weeks.
In a separate interview with Austria's APA news agency, he said the work was "overwhelming and oppressive for investigators".
Mr Fritzl's alleged crimes came to light when Elisabeth's eldest daughter Kerstin, 19, became seriously ill.
She was allowed out of the cellar and admitted to hospital in Amstetten.
Police then issued an appeal to Elisabeth Fritzl to contact them about her daughter, and later picked up Mr Fritzl and Elisabeth near the hospital.
Elisabeth and the children are now in care with the Austrian authorities, who are protecting their privacy at a psychiatric clinic.
Kerstin is fighting for her life in hospital.
Gas threat
Investigators say they have found two heavily reinforced concrete doors that could only be opened by remote control.
Mr Polzer told AP: "They are open now, but we are trying to get another way out of this room because the working conditions in this prison are so exceptional."
He added that officers could "work there only one hour and during this hour they try, one team after the other, to gather everything available in this living space".
Mr Fritzl also reportedly told his victims they would be gassed if anything happened to him.
Technicians are trying to establish if this was more than a threat.
Work in the cellar is expected to take weeks.
In a separate interview with Austria's APA news agency, he said the work was "overwhelming and oppressive for investigators".
Mr Fritzl's alleged crimes came to light when Elisabeth's eldest daughter Kerstin, 19, became seriously ill.
She was allowed out of the cellar and admitted to hospital in Amstetten.
Police then issued an appeal to Elisabeth Fritzl to contact them about her daughter, and later picked up Mr Fritzl and Elisabeth near the hospital.
Elisabeth and the children are now in care with the Austrian authorities, who are protecting their privacy at a psychiatric clinic.
Kerstin is fighting for her life in hospital.
He added that officers could "work there only one hour and during this hour they try, one team after the other, to gather everything available in this living space".
Mr Fritzl also reportedly told his victims they would be gassed if anything happened to him.
Technicians are trying to establish if this was more than a threat.
Work in the cellar is expected to take weeks.
In a separate interview with Austria's APA news agency, he said the work was "overwhelming and oppressive for investigators".
Mr Fritzl's alleged crimes came to light when Elisabeth's eldest daughter Kerstin, 19, became seriously ill.
She was allowed out of the cellar and admitted to hospital in Amstetten.
Police then issued an appeal to Elisabeth Fritzl to contact them about her daughter, and later picked up Mr Fritzl and Elisabeth near the hospital.
Elisabeth and the children are now in care with the Austrian authorities, who are protecting their privacy at a psychiatric clinic.
Kerstin is fighting for her life in hospital.
