LONDON (Reuters) - The world's most dedicated Loch Ness monster hunter has scotched reports that has finally given up looking for the legendary Scottish beast after a quarter of a century of searching.

Last week, the Times newspaper reported that Steve Feltham, who gave up his job, house and girlfriend 24 years ago to look for the creature full-time, had abandoned his long quest, causing ripples among monster-lovers across the world.

But Feltham says he has no intention of quitting his hunt for the prehistoric beast, which legend has it lurks beneath the deep, dark waters of the lake in northern Scotland, although his current best guess is that "Nessie" is just a large catfish.

"It's still a massive world-class mystery," Feltham, who lives in a van on the shores of the loch, told Reuters.

"It's been a life-long passion for me and I'm dedicated to being here and being fully involved in this whole hunt. I couldn't be more content doing anything else."

Feltham said he suspected Nessie was most likely to be a large Wels catfish, a native European fish that can grow up to 13 ft (4 meters) long. Victorians introduced the fish to the loch near Inverness to provide sport.

"At the moment, a Wels catfish ticks more of the boxes than any of the other contenders for the explanation," he said.

"I would like it to be something new and undiscovered rather than something a little bit mundane. People do report four- or five-feet long necks sticking up out of Loch Ness. That's not going to be a Wels catfish."

The first written record of a monster relates to the Irish monk St Columba, who supposedly banished a "water beast" to the depths of the River Ness in the 6th century. Hundreds of thousands of tourists visit every year hoping to spot the monster peeping out from the deep waters.

Four years ago, the driver of a pleasure boat on the loch spotted an object more than five-feet wide on its sonar equipment 60 feet below, where the loch was 600 feet deep.

"That object is bigger than an estate car," Feltham said, adding that explanations for the monster ranged from giant eels and dinosaurs to a spaceship on the bottom of the loch.

"Everybody's got a different theory as to what the identity of the Loch Ness monster is," he said.

(Reporting by Michael Holden; editing by Guy Faulconbridge, Larry King)