Japanese woman Chisako Kakehi was arrested in Kyoto on suspicion of poisoning her husband with cyanide. Picture: Jiji Press

Tokyo - A 70-year-old Japanese woman nicknamed the "black widow" by media said on Wednesday that she could not remember admitting earlier this week to fatally poisoning her husband, local media reported.

Chisako Kakehi, who has been accused of killing three partners and attempting to murder a fourth between 2007 and 2013, told Kyoto District Court she did not recall making the admission on Monday, the daily Mainichi newspaper reported.

Kakehi was arrested in November 2014 on suspicion of having killed her husband Isao with cyanide. 

On Monday, when asked if she had fatally poisoned him in December 2013, she told the court there was "no mistake," the paper reported.

Kakehi said Isao had not treated her as well financially as he had another woman he had dated.

"I wasn't given any money after I married him," she told the court on Monday, according to the Japan Times. "I have no intention of hiding the guilt. I will laugh it off and die if I am sentenced to death tomorrow."

Japanese media have nicknamed Kakehi a "black widow," or venomous spider.

When her trial began in late June, Kakehi said she would leave everything up to her lawyers. 

Her defence team asserted her innocence and claimed her testimony "cannot be trusted due to her dementia," the report said.

Prosecutors say Kaheki has mild dementia but that she can still be held liable for her alleged crimes.

Kakehi lost seven partners in 20 years, including four husbands, within a few years of marrying or starting relationship with them, Japanese media have reported.