"They also had many opportunities to get it right but didn't do so."
Tony Keam, a Korean journalist and former director of World TV, wrote to Tourism Minister John Key in December requesting for the wrong flag to be replaced, but said no further action was taken.
The correction was made today after the Herald approached TNZ.
Spokeswoman Deborah Gray apologised for the delay in correcting the flags and for any offence it may have caused.
"It was never our intention to offend anyone," she said.
"We have sourced accurate files from our teams in market and expect to have them corrected on the site today."