Derby, Reading and newly-promoted Hull are among eight English Football League clubs under transfer embargoes a month before the start of the new season.
The embargoes limit a club's ability to make signings, with sanctions preventing transfer fees being paid.
Fleetwood Town and Gillingham from League One have also been sanctioned.
Swindon Town, already struggling with off-field issues, plus Oldham Athletic and Scunthorpe United are the three League Two teams under embargoes.
The EFL have started publishing a list of clubs under embargoes following a change in regulations voted for by EFL clubs last month.