A spate of street robberies is plaguing suburban Christchurch, with one community leader saying an "ugly trend" is emerging.

Police, however, say the apparent spike was simply a result of pre-quake central city crime being displaced to the suburbs.

Victims in the last month include university students, two women, a tourist and a man who had left a gay bar. Three of the incidents were in Riccarton, the latest of which was in the early hours of Saturday, October 13.

Detective Colin Baillie said a group of university students walking home from the end-of-lectures Tea Party were approached by a group of men in Middleton Park about 12.15am on October 13.

One was knocked to the ground and his hands stood on as the offenders took his cellphone and cash.

The men, described as Maori, aged 18-20, and wearing puffer jackets or dark clothing, left through the park and may have got into a vehicle.

Arrests have been made in relation to the two earlier street robberies in Riccarton, on September 22.

University of Canterbury student Duncan Coleman suffered a badly ripped ear after he was repeatedly punched in the head and face in the Shand Cres Reserve about 2.10am. His watch, cellphone and wallet were stolen.

At 2.30am, four men in their early 20s - three of them students - were walking home in Clyde Rd when they were assaulted by a group of six to eight men after going into a park.

Riccarton-Wigram Community Board chairman Mike Mora said three violent street robberies in the area in three weeks was "an ugly trend".

"We need to stamp it out. People should be able to walk the streets of their suburb safely," he said.

Baillie said different police branches were "coming together" to identify suspects.

Mora said he planned to talk to the Riccarton neighbourhood policing team "to see what could be done".

"There hadn't been an issue up until now [and] I don't think a few extra lights is going to stop these mongrels doing what they are doing."

Detective Senior Sergeant Greg Murton said there appeared to be a problem in Riccarton because the incidents were contained to one area.

Before the earthquakes the same issues were seen in the central city every weekend, he said. "Hamilton has the same problem, Auckland has the same problem. It's no different to how it's been for the last five to 10 years."

Inspector Paul Fremaux said long-term statistics showed street robberies and assaults in Christchurch were trending down. He said the recent cases were "of concern but could reflect a seasonal pattern".

"This type of offending can rise and fall over time," he said.

Fremaux said people needed to "take simple steps to avoid being a victim" such as avoiding walking alone through parks.

Five males aged 16 to 18 appeared in the Christchurch District Court on Friday charged with aggravated robbery over the September 22 incidents. They were remanded on bail without entering pleas.

Coleman, 21, said the arrests over his attack were "brilliant news".

"I'm still pretty terrified to walk by myself at night time," he said.

"We're [students] probably easy targets because we probably never think twice about walking home and there's quite a lot of parks and small streets around here that aren't well lit. I've definitely learnt from my mistake."

- © Fairfax NZ News