Countdown South Dunedin will be monitored for the effectiveness of the additional pest control measures put in place over the weekend.
The store was originally closed for 48 hours from 10pm on Friday, so pest control efforts could be stepped up after four rats were caught at the store over four days.
Woolworths New Zealand director of stores Jason Stockill said pest control service Rentokil had been on site with additional traps and cameras to track any new activity.
"We believe all entry sites have been identified — and now sealed — and can confirm there continues to be no evidence of nesting in store," he said.
"Our team and contract cleaners are continuing to focus on cleaning throughout the store," Mr Stockill said.
Ministry for Primary Industries division New Zealand Food Safety was on site observing and supporting Countdown’s pest control programme and work, he said.
A second pest control contractor had also been observing.
The Ministry for Primary Industries said it would be involved in the decision-making about when the store reopened.
The South Dunedin supermarket came to national attention last month after staff members told the Otago Daily Times rats were running rampant in the store and they feared the public could have been sold contaminated food.
A photo, taken in November last year, was then supplied to the ODT showing a rat in the deli section.
On Friday, Mr Stockill said he thought the issue had been addressed since there had been no evidence of rodent activity since January 28, but having caught four rodents in just a few days meant there was more work to do.
An employee, who asked not to be named, said on Friday, while the store’s rat issue had been taken seriously of late, the initial response was slow.
"From the beginning, management minimised this, saying there was one rat," they said.
"We lost a lot of time with that, trying to convince management that this was a problem."
Staff had also been rostered on during the weekend and were expected to go in and do a deep clean.