Some 3316 vehicles registered to Auckland addresses fled to the far north in the 6 hours before the Level 4 lockdown kicked in last month.
The data comes from the automatic number-plate recognition (ANPR) camera system on the Northern Gateway Toll Road north of Tāmaki.
The revelations have prompted a "please explain" to the government from National deputy leader Dr Shane Reti.
“Not only have several thousand people brought their Auckland risk into Northland, but this has also unfairly burdened Northland infrastructure during Level 4 including supermarkets, health and police resources,” Reti says.
Iwi leaders including former parliamentarian Hone Harawira who established border patrols into the region were scathing of the new arrivals at the time.
“The Government should’ve planned for a future lockdown and worked on a strategy so that the Northland boundary could be implemented far sooner,” Reti said.
Speaking to Te Ao Māori News earlier this month Police Deputy Commissioner Wally Haumaha acknowledged the police response would be looked into.
'There certainly was an influx of people going to the north and we're conscious of that. It's something that we will discuss at the end of this,' he told Te Ao Tapatahi.
Northland was kept in level 4 lockdown alongside Tāmaki for several days after the rest of the motu moved to level 3 over concerns the virus could’ve crossed into the region with travellers from Auckland.
The Ministry of Health said a rest home worker testing positive in Warkworth (on the Tāmaki, Northland border) was another reason for the extended level 4 lockdown in Tai Tokerau.