A Japanese teenager is still feeling the effects of a concussion suffered when he and his older sister were terrorised and assaulted near a Christchurch park by two youths while they were out jogging.

Their mother has spoken out after the racially motivated attack left both her children needing treatment for injuries.

The Japanese consulate has also issued a warning to members of the ex-pat community to be vigilant when walking the streets.

Naomi Suzuki told The Christchurch Star her 14-year-old son and 17-year-old daughter were running on Harewood Rd, opposite Bishopdale Park, about 5pm on May 31 when they were chased down and attacked by two males.

Her children were about to cross the intersection of Cotswold Ave when the assailants, described as European and aged between 17-19, yelled at the duo and gave chase.

"They thought it was creepy and sped up, but they didn't take it seriously since teenagers sometimes act weirdly," Suzuki said.

However, the incident turned sinister when the youths caught up with the siblings.

They tried to trip up the 14-year-old and then placed him in a headlock before punching his left eye.

The sister was also kicked in the chin as she fell while trying to protect her brother.

During the five-minute ordeal the brother repeatedly asked: "What did we do?" The only response the siblings heard was one of the youths saying: "You ate my dog."

While the pair were pinned up against a fence, a teenager on a mountain bike told the attackers to stop; a passing motorist also slowed down and tooted.

"They say things could have gotten a lot worse if that car didn't toot to us," Suzuki said.

After the attackers fled, the siblings returned home and were then taken to Christchurch Hospital.

The brother suffered blurred vision in his left eye, and his sister had a bruised and swollen leg.

They were interviewed by police, who were already at the hospital, in the emergency department and also reported the incident the following day.

Suzuki said she was frustrated with the response.

"According to the woman at the counter (at the police station) it would only be possible to find those teenagers if there is any CCTV or witnesses around the area.

"There are no signs of CCTV or security cameras in the area."

She hopes motorists and other witnesses will come forward as the incident may have been captured on a vehicle dash camera.

Suzuki said her son, a keen runner, is still affected by dizziness after light exercise.

"He has some headaches and a lack of concentration during school and other studies," she said.

She said one of the teenagers was wearing a black hoodie and black trousers and was of medium build.

The other attacker was slim with short, curly brown hair. He was wearing a black jersey and black pants.

The siblings are the latest victims of anti-Asian sentiment in the city, which intensified following the global spread of Covid-19 from China.

In February last year, two "skinheads" abused a group of Asian students over the coronavirus while the children stood outside Merrin School in Avonhead.

Earlier that month, an email sent to parents in the Rolleston area called Asian people "virus spreaders" and said they should be barred from attending schools. Last October, a Chinese university student was abused by a woman on the Orbiter bus in Burnside.

Gordon Huang, who had been in New Zealand for three years at the time of the incident, credited the driver and a teenage passenger for defending him before the woman exited the bus.

- text by Chris Barclay, Christchurch Star

Information on the Bishopdale incident can be passed to police by calling 105 and quoting file number 210601/2066 or through Crimestoppers – 0800 555 111