Motherwell could take their case for Chris Cadden compensation to FIFA as early as next week, PA understands.
The Ladbrokes Premiership club had not heard back from Columbus Crew 48 hours after requesting training compensation.
The Major League Soccer side announced the signing of the 22-year-old on Tuesday and immediately loaned him to Oxford.
The MLS only agreed in April to start abiding by the international system of compensating clubs for developing young players. But there has been no confirmation of the ranking of American clubs.
Motherwell believe Columbus Crew are a Category 2 club and should be paying £200,000 for the Scotland international, who rejected a new deal at Fir Park under FIFA’s compensation formula. The Americans have an annual player wage budget of almost £10million.
However, they fear Columbus will argue they are a Category 4 club, similar to the likes of League Two clubs in Scotland, who do not have to pay compensation.
Oxford were also trying to sign Cadden on a permanent deal this summer and would have been due to pay close to £400,000.
Manager Stephen Robinson said: “We are due compensation so that will be an ongoing thing.
“What’s the point in developing players from nine years of age and then they can just walk out with a loophole?
“We will certainly be taking that further.”