An elderly man who fell over in a public toilet in Christchurch had his phone stolen after calling out for help. 

On Saturday, 92-year-old Gordon Proctor fell over in the toilet in the suburb of New Brighton, Star News reports. 

Proctor screamed out for help and a man entered the bathroom, but instead of helping, he stole his phone.

Proctor told the Star he was "lying on the cold concrete floor shivering".

The offender is said to be aged in his early 20s.

Another New Brighton woman also heard Proctor calling for help.

"He [Proctor] was in quite a state for a while," Bindi Donaldson told the Star. "He was saying 'my phone' just after I entered the bathrooms."

A police spokesman confirmed to Newshub the theft of the cell phone was being investigated.

Inquiries were ongoing and no further information was available, he said.