An unstable cliff face has forced the evacuation of two homes in the Christchurch beachside suburb of Sumner.

Earlier today a slip caused damage to one garage and one house in Wakefield Avenue.

Nobody was injured but those evacuated by police may not be able to return to their homes for some time, said Christchurch City Council spokesman Terry Sefton.

Staff from the Earthquake Commission (EQC), ECan, police and Christchurch City Council were at the site this afternoon investigating the stability of the cliff face.

The full investigation could take several days, Mr Sefton said.