The accident occurred between a vehicle and a motorcycle on Mt Albert Rd, near Dominion Rd.
A stationary police vehicle witnessed a motorcyclist travelling at very high speed on the Southwestern motorway, he said, before losing sight of the motorbike.
Police then began making area inquiries to locate the motorbike.
Another police vehicle saw the same motorcycle on Mt Albert Rd travelling in the opposite direction a short time later.
The police officers then made a U-turn in an attempt to follow the motorcyclist but immediately lost sight of it in the distance.
They then located the crash scene further along Mt Albert Rd.
"Police want to clarify that at no point was the motorcyclist signalled to pull over by police and there was no pursuit," police said in a statement.
The Serious Crash Unit is investigating the crash.
The spokesman said the Independent Police Conduct Authority was not notified because it was not a fleeing driver incident.
Police said the motorcyclist has been transported to hospital in a critical condition.
A section of Mt Albert Rd was closed and the Serious Crash Unit was in attendance.
Resident Phillip Gorman said he saw the motorcyclist heading along Mt Albert Rd towards Sandringham Rd when the male motorcyclist spotted a police car and did a U-turn back towards Dominion Rd.
The police car pursued the motorcyclist at well over 100km/h, Gorman said.
This is in contradiction to the police account of what happened.
Gorman said a flatmate saw the motorcyclist hit a car at the intersection of Mt Albert Rd and Dominion Rd. It looked like the motorcycle had gone under the car, which sustained considerable damage.
"This is a situation that should not have happened. Why go at high speed chasing a motorcyclist? It would have been better to let him get away," he said.
"Less than 48 hours ago we had a police dog van chasing a vehicle in South Auckland with the two occupants and the policeman going off to hospital in a high speed chase," Gorman said.
"Let's bear in mind a couple of years ago, because of these chases, there was a directive at government level to the police to discontinue these chases at a certain speed."
A Mt Roskill Rd resident said he heard police sirens go off for around 20 seconds and the sound of a "high powered racing bike" zooming away and then back.
"Even if there isn't an active pursuit, the motorcyclist must be fleeing police when he heard the sirens," he said.
"After about 20 seconds then it just went silent, that was probably when the crash must have happened."
He rushed to the scene and saw four police officers attending to the injured motorcyclist.
