Motherwell are considering a winding-up order against Cardiff to recoup money owed on the transfer of Paul Quinn.
Cardiff failed to pay £100,000 due in January and a further £75,000 summer payment has also not been forthcoming.
The Fir Park club issued a writ against Cardiff at Hamilton Sheriff Court on Friday but say that the Welsh club did not attend or submit a defence.
In response, Cardiff chief executive Gethin Jenkins said the matter would be settled within a week.
The statement from Motherwell was issued shortly after Cardiff signed Craig Bellamy on loan from Manchester City.
And Jenkins was asked about it during the media conference to present the Wales striker.
"I see they jumped in ahead of us," he said. "Our lawyers have been in communication with them and it will be resolved within the next seven days."
"But I should stress these are loans and any signings we've done so far have been frees."
Motherwell first expressed their dissatisfaction at the situation on 22 July and say Cardiff made an approach to work out a solution ahead of Bellamy's unveiling.
"They offered staged and part payment and possibilities but nothing hard and fast," Motherwell chief executive Leeann Dempster told BBC Radio 5 live.
"The simple facts are we are owed an undisputed debt, it's well overdue and we don't want part payments - they have not honoured those before.
"They have signed a high-profile player, which has really annoyed us. They should have their debts settled from last year before they are allowed to sign any players."
In an earlier statement, Dempster added: "It is critical that clubs work constructively with each other to ensure we can manage a very difficult financial climate for the game. We have given Cardiff every chance to do the right thing.
"The board now believe that Cardiff's position is untenable given their activity in the transfer market acquiring Jason Koumas, Tom Heaton, Danny Drinkwater, Seyi Olofinjana, Martin John and today, the loan signing of Manchester City's Craig Bellamy.
"Given all these circumstances and with legal and moral weight behind us, Motherwell FC have no option but to immediately pursue all legal routes to ensure this significant sum is paid to us as quickly as possible.
"These may include issuing a winding up order, arresting assets or physically sending bailiffs to their ground on match day to take possession of cash. Every option will be fully considered and implemented as soon as possible.
"We want Cardiff fans to know that we appreciate the concerns this will give them. We can only urge them to look to how they would feel in our position and urge them to put pressure on their own board to ensure the excellent long-term reputation of their club is not diminished by the leadership of one board.
"We have a job to promote and protect the interests of our own employees, fans and shareholders and we will. We would also suggest to the Championship and the English FA that they look with great care at the conduct of Cardiff in handling this matter.
"Even at this very late stage, I would urge Gethin Jenkins of Cardiff to pay this money plus costs and interest by return in order to save his club acute embarrassment and the football community in general unwarranted bad publicity."
Jenkins has accused the Lanarkshire club of having "jumped on the publicity" of the Bellamy signing, something Dempster rejects, despite club chairman John Boyle's appeal on television for the payment to be made.
She told BBC Radio Scotland's Sportsound: "We were accused today of jumping on the bandwagon. That's farcical. That's certainly not what we are doing. We could have gone public about this a lot sooner.
"John wouldn't have been all over the TV screens today if they had honoured their debt. That's the simple fact of the matter."
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