The scheme is expected to help the fortunes of Cardiff City FC

Cardiff Council made the demands after club officials asked for an extra six months to secure the project.

The council said it was not satisfied with the business plan that the club has delivered.

But club officials said that they were "fully confident" that the scheme was a viable project and would go ahead.

The club has already committed �3m to the scheme which would see a new stadium built opposite its current Ninian Park home in Leckwith.

The �100m stadium plans are seen as essential to the future of the Championship club.

Intergral to the scheme is securing retail development alongside it and it is this aspect which has become a source of concern for the council, which has committed nearly �500,000 to the scheme.

American discount store group CostCo earlier this year signed a contract to become a tenant but other stores are needed on board before the plans can go ahead.

Following a meeting between the club and the council's economic scrutiny committee, the council demanded that the club prove that the scheme could satisfy pre-conditions laid down in a development agreement ensuring viability of the project from 31 December.

I'm absolutely confident that this scheme will go ahead and provide Cardiff with an exciting and vibrant future Peter Ridsdale, Cardiff City FC

This includes providing a business plan showing how the project can be delivered and also demonstrating that the club is financially strong enough to see the project through to completion without further financial assistance from the council.

The club has a �30m in debt and has already acted to reduce the wage bill.

Chairman of the committee, councillor Ralph Cook said: "The committee thoroughly examined the issues over the stadium plans and there was clear scepticism over whether the development can go ahead and the committee supported the officers' recommendation regarding the deadline given granted to the club.

"This is the time for all involved to get their heads down and ensure a viable business plan is in place for the March deadline.

"I sincerely hope this can be achieved," he added.

But the club reacted by saying it has been unable to deliver a full business plan because of on-going talks with a food retailer - believed to be a major supermarket group - who has yet to give a conditional assurance they will take an outlet.

Club deputy chairman Peter Ridsdale told the BBC news website that he was confident that a deal would be made by the end of this year with the retailer with a full business plan being submitted in February.

"The issue so far has been securing the food retailer but I am confident that by the end of this year we will have got a conditional offer from them," he said.

"And once we have that we will be able to submit our business plan. We have not been able to do that so far because we have been waiting for the retailer.

"I'm absolutely confident that this scheme will go ahead and provide Cardiff with an exciting and vibrant future," he added.