WARSAW (AFP) - A 91-year-old Polish woman surprised morgue workers when she started moving, 11 hours after being declared dead at home, public television reported Thursday.

Janina Kolkiewicz woke up inside a body bag in a cold chamber at the morgue in eastern Poland last Thursday, according to the TVP public broadcaster.

"I was sure she was dead," doctor Wieslawa Czyz told TVP. "I'm stunned, I don't understand what happened. Her heart had stopped beating, she was no longer breathing," she said.

"My aunt has no inkling of what happened since she has late-stage dementia," Bogumila Kolkiewicz, the woman's niece, told a local newspaper.

"Once we got her home, she said she was freezing and asked for a hot cup of tea."

Police have opened an investigation into the incident.