Britain's appeals court has increased to 20 years the prison sentence of a surgeon convicted of performing unnecessary operations, leaving scores of patients maimed and some in constant pain.

Ian Paterson falsely told patients they had cancer and performed operations including mastectomies. He was convicted of crimes against 10 patients in May and sentenced to 15 years. Prosecutors believe there were many more victims.

The government challenged the sentence, and three appeals judges agreed Thursday that it was "unduly lenient."

One of the judges, Heather Hallet, said "greed, self-aggrandizement, power" and other possible motives "do not come close to explaining how a doctor can falsely tell a patient he or she has cancer when they have not."

She said the victims "must feel no sentence could properly reflect their suffering."