Police saw a motorcyclist doing 261kmh on State Highway 73 on Saturday evening. The motorcyclist has not been caught.

A motorcyclist has been clocked doing more than two-and-a-half times the speed limit near Christchurch.

Acting Canterbury Road Policing manager Scott Richardson said police saw a motorcyclist doing 261kmh on State Highway 73, near West Melton, about 8.27pm on Saturday.

The motorcyclist had not been caught. They were wearing all black and riding a black road bike.

Richardson said 261kmh was the highest speed recorded in Canterbury since he joined road policing in 2007.

Police needed to identify the person "before they kill themselves or an innocent".

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On Thursday, police caught another driver going 181kmh in a rental vehicle on State Highway 1 in North Canterbury. The driver was suspended from driving for 28 days and would appear in court on a charge of dangerous driving.

"People travelling at these speeds have no regard for themselves or other people on the road," Richardson said.

"We need people to slow down, if not for their own sakes, for the sake of other people sharing the road."

Richardson said the statistics were "shocking".

"At 261kmh you are travelling 72 metres per second. If a car pulled out or a sheep walked out onto the road, you would have no chance.

"With reaction time that means a total stopping distance of 406m. At 350m the bike would still be doing over 100kmh, that's instant death to the rider and quite possibly any other road user they hit."

Speed was the "single biggest" factor in whether a crash was minor or fatal.

"It is pure physics, the human body is not designed to withstand extreme forces."

Police wanted people to have a safe summer, "free of the pain and trauma of a road crash", Richardson said.

"It's about everyone taking responsibility for their own driving and safety.

"Christmas is supposed to be a time for family coming together for celebration, not a funeral."

The country's road toll for 2015 was at 309 after a nightmare 24 hours on the roads - 30 higher than for the same time last year.

The road toll for Canterbury stood at 44 after a young man died in a crash in Halswell about 1.15am on Friday.

Richardson said speed was a factor in the crash.

The Canterbury road toll was 33 at the same time last year.