Finnish crime novelist Tuula Sariola has shocked her publishers and fans by admitting she did not write her 16 books after all.

The widow of best-selling author Mauri Sariola has revealed her books were actually "ghost written" by her longtime friend, Ritva Sarkola, Helsingin Sanomat reported.

Gummerus Publishers editor Paula Pesonen said the revelation was a shocker.

"I am extremely surprised and shocked over the situation, and I can only say that I feel sorry for all parties," Pesonen said.

As for Sarkola, she is getting ready to put out her "first" novel under her own name, the newspaper said.

Sarkola said she had promised Mauri Sariola she would help his wife.

"I am relieved that Tuula admitted the truth about our cooperation in the writing of books," she said. "We both hope that handling the matter in public would end here."

Mauri Sariola wrote 90 books prior to his death in 1985.