A two-kilogram gold nugget has been unearthed by one lucky prospector in Victoria.

The prospector - who understandably wishes to remain anonymous - dug up the nugget on the outskirts of Ballarat, a one-time gold rush town.

Prospecting gear supplier Mark Day of Gold Ballarat said the man, a retiree who was a customer of theirs, had already received offers of $160,000 for the nugget.

A man unearthed a 2kg gold nugget near Ballarat. (A Current Affair)

"I’ve been in this business for 25 years and this is the biggest find we have seen by one of our customers – that they’ve told me about anyway," he said.

Mr Day said the man had been searching in old pastureland when his detector went off.

After unearthing a .22 lead bullet, the prospector thought that was it, but his detector kept "insisting" there was something further down.

About a metre deep, he found his treasure.

Mr Day said the digger contacted them afterwards.

The man has already been offered $160,000 for the piece. (A Current Affair)

"I said I wasn’t a buyer and asked him what he meant by big. He said two kilos and I just said, ‘You’ve got to be kidding!'," Mr Day said.

"When he showed me the nugget here in the store he was shaking like a leaf. He didn’t know what to do with it. He hadn’t slept in three days."

Collectors were lining up to buy the nugget, he said, which was set to fetch a premium because of its size and shape.

The prospector, meanwhile, purchased a new top-line detector from Mr Day's store and set back out into the bush.

"He certainly thinks there's more gold out there," Mr Day said.

"And after this, who can say he's wrong?"