"In the recent attacks, a Wellington taxi driver was subject to a brutal attack by a person who followed him to Wellington Airport in mid-afternoon," Hart said.
"The attack had racial overtones and the attacker opened the driver's door and leapt on top of him, punching him about the head."
Hart said the attacker was dragged away by other taxi drivers, "still shouting racial abuse and threatening further attacks".
He said the attacker was held until police arrived who arrested him and two others waiting in a car nearby.
A second incident took place this morning in Manurewa, South Auckland, Hart said.
"Three youths, aged around 17 or 18, attacked a taxi driver and demanded money."
He told the Herald the three youths had been passengers in the cab.
"He was punched repeatedly around the head but was able to use his duress alarm to summon help. The three youths took off on foot when help arrived and the driver was taken to hospital by ambulance."
Inspector Adam Pyne, the Manurewa area prevention manager, confirmed at about 12am a taxi driver was attacked while parked in the taxi stand in the Southmall car park in Manurewa.
Pyne said three young males approached the victim asking for a ride.
"When the victim asked for payment upfront the three males carried out a violent assault, punching and kicking him. The victim managed to call for help and police were contacted."
Pyne said police were immediately deployed, however, the offenders had fled the scene.
The victim was taken to Middlemore Hospital with moderate injuries.
"We are currently in the process of gathering CCTV footage and making further inquiries," Pyne said.
Hart told the Herald the driver from this morning's attack was "badly shaken" and in shock and recovering from the attack.
"He's at home and trying to get himself ready to go back to work and to earn a living."
Hart said when a driver activates a duress alarms the car becomes "live" and operators at the taxi base can hear what is happening in the vehicle, pinpoint its location, and direct police and other drivers to the scene.
"Taxi drivers provide a service round the clock but with changing drinking patterns and drug use more anti-social behaviour is being encountered," he said.
"The changes to the Land Transport Act are still before Parliament awaiting a second reading and on behalf of taxi drivers throughout New Zealand we make a plea to Members of Parliament to ensure a safer work environment for people providing this essential service."