A "pure evil" pensioner who trafficked a deaf and mute girl aged about 10 from Pakistan and kept her in a cellar to claim benefits, has been convicted of repeatedly raping her.

Ilyas Ashar, 84, was found guilty of 13 counts of raping the victim, who is now in her 20s.

Ashar had kept her at the home he shared with his wife Tallat in Greater Manchester, England.

The victim was made to sleep in a "sparse, cold and damp" cellar.

A jury at a re-trial in Minshull Street Crown Court heard the girl was beaten and slapped as well as being forced to work in virtual slavery as a domestic servant, British media reported.

Her ordeal was revealed when she was accidentally found in 2009 by trading standards officers who went to the house to investigate possible illegal activities.

Ashar used his victim to satisfy his sexual desires as well as enlisting his wife to use the girl's details to steal more than £30,000 (NZ$57,000) in benefits as well as set up several bank accounts in her name.

Ashar was convicted at an earlier trial of two counts of trafficking a person into Britain for exploitation and three counts relating to the fraudulent obtaining of benefits.

Tallat Ashar, 68, and the couple's daughter, Faaiza Ashar, 46, were found guilty at the previous trial of benefit fraud charges.

Police said Ilyas Ashar was "pure evil", obtaining and exploiting a victim who had no means to communicate and no contacts beyond his family. Despite her treatment, the victim was now confident, well-adjusted and determined.

The victim was brought into Britain through London's Heathrow airport in 2000, when she was aged about 10, using a passport which gave her age as 20.