Uefa president Michel Platini said today that he was unhappy with the transfer system and was considering asking for a review into possible changes.
Under current rules, players can be transferred from the close of the previous season until midnight on 31 August. The window then re-opens on 1 January and closes again on 31 January.
Though they cannot represent their new clubs in the Champions League or Uefa Cup if they have already appeared in the competition that season, they are free to play in domestic league football.
"I don't think a player should be able to play for two clubs in the same competition in the same season and I think we need to get the (Uefa) Strategic Committee to look at the whole idea," Platini told Reuters.
"I think that it is wrong that a player can play for two clubs in any competition, scoring a goal for one team one week and then scoring against them a few weeks later.
"I also think we have to look at both the summer and winter transfer windows. The season starts in many countries in July or early in August, yet the transfer window does not close till the end of August.
"Then we have another window in the middle of the season. I think we need to look at the way the system works."
The Strategic Committee met today to discuss a range of issues, including a ban on the transfers of minors - players under 18 years of age.
Uefa also wants to implement a new rule that young players under 18 should have to sign a "first contract" with the club that first develops, trains and educates them, up to 18.
"We cannot force a young player to sign for his first club after that age," Platini said.
"But at least if they signed a first contract at 13 or 14 then they would have a period of stability in their careers while they are being developed as young players."