FIFA have initially denied Swansea City's bids to acquire Daniel Sifu and Rafik Halliche.
The club had agreed a fee with French side Lens for Sifu, while a loan deal was struck with Fulham on transfer deadline day for Halliche.
"Due to minor delays in processing the transfers, FIFA has informed the club that they will not grant international clearance for either defender," the Swans said in a statement.
"This is despite the full backing of the Premier League, the FAW, FA, French Federation and the PFA."
The club added that they are "disappointed" by the decision but will wait for written confirmation before considering an appeal.
