It bounded out in front of their car – a black panther-like cat moving at speed.

Marlborough woman Juliearna Kavanagh, from Picton, says she was stunned when a huge animal leapt across the road, just a few feet in front of the car she was in just before Ward on the east coast of the South Island.

The business owner is warning people in the area to be careful in case the creature attacks.

A huge black cat leapt in front of Juliearna Kavanagh's car, she says. Photo / Supplied

She has contacted police and Ministry of Primary Industries about the encounter.

"It was in full flight; it was big and sleek and with a cat's head and a huge tail," she says.

Along with partner Warren Lewis, Kavanagh was travelling on SH1 about 11.30pm, returning from Invercargill on Friday.

Kavanagh, who owns and operates the Hop on Hop off wine tour company in Marlborough and Queenstown, says the strange encounter has left the pair bewildered.

"We both looked at each other, thinking what the heck had just happened?

"We pulled off the road, slightly hysterical and went through every animal that it could possibly be, but nothing made sense.

"It was shocking," Kavanagh said.

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There have been numerous reports of large cats in New Zealand's South Island, with some dating back to the early 1900's.

A pregnant puma was documented as having escaped from a circus in Lyttleton Harbour and the possibility of using cougars was discussed as a way of controlling the thriving deer population in the Canterbury foothills.

But officials have always deemed the sightings to be of a feral cat.

Kavanagh says she had slowed down to go around a bend when the cat leapt across the road.

"It was just there, right in front of our headlights, right out of the blue. It was so quick; it was either chasing something or had heard our car."

The Escape to Picton hotel owner says she has no doubt that what she saw was a puma.

"I couldn't live with myself if I'd kept quiet and then it attacked a small child or livestock.

"A big cat isn't the first thing that we naturally thought of, after all we don't live in a country where you expect to see them. But that's what it was," she says.

"I don't scare easily, I've seen some s***, but it was big, quick and black and I was struck by how big its tail was.

"If that was a feral cat, it's a feral cat on steroids. Curiosity killed the cat but it's not the cat I'm worried about."

Ministry of Primary Industries has been contacted for comment.