Plans to turn a disused quarry in Llanberis into an outdoor sports centre have received a set back.
Two companies have put in bids to develop the site
Gwynedd Council invited two companies to present cases for redeveloping Glyn Rhonwy quarry as a mountain bike centre or a ski complex.
But the council said there were fundamental weaknesses in both cases.
The companies - Becio Llanberis and Adwy Eryri - will now reconsider their plans to redevelop the 75-hectare (185-acre) site.
The council working group said it was concerned whether there was a strong enough market in north Wales to sustain the outdoor activities the companies are promoting.
Councillor Trefor Edwards, chair of the working group, said: "We have here two exciting schemes for the area but unfortunately the evidence within the business cases as they stand isn't enough to convince us that the developments could be realised and that they would thrive.
"The Glyn Rhonwy site is a special asset to this area and it would be extremely irresponsible of us to earmark the land for a development without a robust business plan."
Mr Edwards said bids from other companies would now also be invited.
Becio Llanberis - set up by a group of local bike enthusiasts - has said it wants to create Britain's best mountain biking venue.
And Adwy Eryri want to turn the quarry into a year-round leisure complex featuring Britain's longest ski slope.
But Gwyn Pritchard, from Adwy Eryri, said he was confident he can alleviate some of the council's anxieties.
He said: "What we have to do is create a new market - we need to bring more people in, not rely on the existing people coming in.
"We live within two hours of eight million people so we really have to market that with a different strategy and we've got plans to do that."
Ted Silvester, one of the directors of Becio Llanberis said he was disappointed at the council's decision, but told BBC Wales the company could improve its bid.
"It's a fairly new product that we're proposing in the mountain bike world," he said.
"We've fallen down in sufficiently proving to an independent observer that the figures add up, so this is obviously an area we need to go away and do more work on."