At least two women may have been tortured to death by a man and his ex-wife at a house in western Germany, according to investigators.

Prosecutor Ralf Meyer said a 33-year-old victim was chained and beaten after responding to a lonely hearts advertisement and moving into the house in autumn 2013.

"There was serious physical abuse - beating, being chained to a radiator, having to sleep on a cold floor," Mr Meyer said.

The woman died on 1 August 2014 and the body was cut up and stored in freezer, he said.

Pieces were removed over time and burned in the fireplace.

The victim's phone was used to continue to send text messages to her mother long after her death.

Last month a second woman, Susanne F, 41, died in hospital from injuries police say were related to torture.

It was her death that led police to the house in Hoexter on the border of Lower Saxony and North Rhine-Westphalia.

A third woman may also have been tortured to death and police say there are indications others may have survived abuse at the house.

A man and his former wife - identified only as Wilfried W and Angelika B due to German privacy laws - are in police custody in connection with the deaths.

Mr Meyer said Angelika B, 47, had confessed but said she was under the spell of her ex-partner, who is 46.

Ralf Oestermann, chief of the homicide division in the nearby city of Bielefeld, said she had been "massively abused" by her co-accused.

Wilfried W has denied any guilt.

Mr Meyer said the investigation showed the pair were not driven by sexual motive but by the desire to "exert power".

"There are indications of sadistic tendencies," he told German news agency DPA.

Police have sealed off the building, which German media have described as a "house of horrors", while investigators search for clues.