New Zealand police on Friday dismissed a fresh reported sighting of missing British girl Madeleine McCann, nearly six years after she went missing while holidaying with her family in Portugal.

The latest suspected sighting was on New Year's Eve in the resort town of Queenstown and in the same southern region of New Zealand where there have been other claims the youngster has been seen in recent years.

However, Queenstown detective sergeant Brian Camerson said police were "absolutely satisfied" the child was not Madeleine and it was not the first time someone had noted a similarity between the two girls.

The woman who reported the sighting told the Southland Times newspaper a girl resembling Madeleine had entered her store with a dark-haired man on December 31.

"She had the same eye defect as Madeleine. Only a very small percentage of the population have that and I was just staring at it the whole time to the point I forgot what they had purchased," she said.

"My only reason for alerting anybody is because if my little girl was missing and if someone on the other side of the world was seen who bore any considerable resemblance, I would want it ruled out."

Madeleine was only three years old when she disappeared six years ago. In a Christmas message posted recently on their findmadeleine.com website, her mother Kate thanked people for continuing to care.

"It is both heart-warming and reassuring to know that after all this time Madeleine still remains in so many people's hearts and minds. This solidarity and commitment gives us great hope. Thank you," she wrote.

"We are very aware that without public help it will be virtually impossible to find Madeleine."