An elderly woman has been questioned by police after allegedly keeping her mother's body in a freezer for up to two decades, it emerged today. Police found the body wrapped in a black bin liner in a chest freezer at a semi-detached house in Sidcup, south-east London.

Officers interviewed Daulat Irani, 83, under caution after the body was discovered and identified as that of her mother Gulbai Freedoon Murzan, who was born in 1901. Police believe she may have been dead for up to 20 years.

Metropolitan police said the death was being treated as unexplained, rather than suspicious. Postmortem results are expected later this week.

It is understood that officers were called to the property in Park Mead on 10 May after being alerted by a neighbour, and forensic officers removed the corpse.

It is unclear why the body was kept in the freezer, but neighbours of the elderly woman suggested she may have been worried that immigration authorities would discover her mother had been living illegally in the UK.

A neighbour, who did not wish to be named, said Irani was a "very private person" who kept her garden in pristine condition. "Obviously it was shocking when the police came and told me what happened. They said they believed she had been in the freezer for more than 20 years," the neighbour told the Daily Mirror.

"I think it was an immigration thing because her mum was illegal and they didn't want anyone to know."

Ray Dyson, 77, who lives nearby, said Irani was a "nice old lady" who went quietly about her business. "This has all come as a bit of a shock. The first we knew was when two police cars and an officer in a full forensic bodysuit turned up. They taped off the garage and have now put a padlock on it."

Another neighbour believed Irani had confided in a friend, who had passed on the information to police. "I saw her after the police visited and she told me they questioned her for hours. I told her it wasn't surprising considering what they had found. She said the police were going to contact her again soon."

A police spokesman said: "We can confirm that we went to a residential address in Sidcup. Officers found the body of a woman. We believe we know the identity but await formal identification. The death is being treated as unexplained. An 83-year-old woman has been interviewed under caution but there have been no arrests."