A Christchurch man convicted of repeatedly raping his daughter over a three-and-a-half year period was jailed today for 15 years.

The man, unemployed and in his 40s, cannot be named because it would identify the victim of his offending.

His daughter was aged between nine and 12 at the time of the offending, which ended in October 2004.

The man had pleaded not guilty at the Christchurch District Court to two charges of unlawful sexual connection and rape. The jury at his four-day trial last month found him guilty of two charges but acquitted him on the third.

Prosecutor Jane Farish told the jury the charges were representative counts, meaning that the offences had occurred more than once.

Defence counsel James Rapley submitted the man could have been sentenced on the basis that the offending was akin to incest, but Judge Gary MacAskill rejected that, saying the girl was too young for it to be considered.

He said he was sentencing the man to 15 years' jail on the conservative basis that there had been 20 instances of rape over the period of the offending, and three instances of digital penetration.