Barcelona will be barred from signing players until January 2016 after Fifa rejected an appeal against their transfer ban, imposed in relation "to the protection of minors".
The news that they are banned from the next two transfer windows will be a massive blow for the Spanish club as they look to compete against domestic rivals Atletico Madrid and Real Madrid and on the European stage.
Fifa imposed a 14-month ban on Barcelona in April this year after the club were found to have breached rules on the signing of international players under the age of 18.
However, the ban was suspended pending the appeal.
During that time, the three-time European Cup winners managed to bring Luis Suarez in from Liverpool for a fee in the region of £75m. They have also signed Claudio Bravo from Sociedad for £9.5m, Jeremy Mathieu from Valencia for £15.8m and Thomas Vermaelen from Arsenal for £15m.
Video: The latest transfer news
Despite having made an outlay in the region of £115m this summer following their failure to land a single trophy last term, the Catalan club may be keen to do more business in the final few days of the current transfer window before the ban comes into action.
A statement from Fifa today read: "The Fifa appeal committee has decided to reject the appeals lodged by Spanish club FC Barcelona and the Real Federacion Espanola de Futbol (RFEF) and to confirm in their entirety the decisions rendered by the Fifa disciplinary committee in the respective cases relating to the protection of minors."
The 10 biggest transfers that could still happen
The 10 biggest transfers that could still happen
1/10 Radamel Falcao - Manchester United
Despite missing more than six months with injury, the Colombian striker remains one of the hottest properties in Europe. Falcao had been linked with a move to Real Madrid, but Arsenal and Manchester City had been linked with a move on deadline day for the striker. Enter Manchester United, who pulled off the shock of the summer after a season-long loan was agreed in principle with a view to a permanent deal.
2/10 Sami Khedira - Arsenal/Chelsea
Will he, won’t he, will he, won’t he? Sami Khedira is clearly surplus to requirements at Real Madrid after the arrival of Toni Kroos but his wage demands and fee seem to be getting in the way of a resolution. He is a fantastic player and would be a major coup if he were to arrive at either London club, but this transfer will probably rumble on until deadline day
3/10 Edinson Cavani - Liverpool
Another striker unhappy in Ligue 1, Cavani scored 25 goals for PSG last season but is reported to be unhappy playing second fiddle to Zlatan Ibrahimovic in Paris. PSG don’t want to sell, but Brendan Rodgers is looking at the top end of the market to replace Luis Suarez and could spend big on Cavani or Falcao
4/10 Mehdi Benatia - Manchester United
The classy Moroccan centre-back would perfectly fit the profile as one of the back three in Louis van Gaal's system. The Roma man, believed to be available for about £30m, is very good on the ball, an excellent athlete and a fierce competitor. He is comfortable taking the ball forward and is a threat at set-pieces
5/10 Arturo Vidal - Mancester United
This potential transfer seems to have been rumbling on all summer but appears unlikely. Vidal is supposedly keen on a move and a midfielder of Vidal’s quality would be an upgrade over United’s current crop, but Louis van Gaal is believed to have doubts about the Chilean’s knee
6/10 Petr Cech - Real Madrid/PSG
Jose Mourinho wants Cech to stay in west London but the giant goalkeeper is too good to waste his away on the Chelsea bench. Real Madrid, Monaco and Paris Saint-Germain seem the likeliest destinations for the 32-year-old, who is still one of the very, very best in the world
7/10 Mats Hummels - Manchester United
Again, this deal appeared to be dead after Jurgen Klopp said he had no intention to sell and made the World Cup hero his club captain. But rumours for the German centre-back continue to swirl and given United’s defensive woes – Tyler Blackett is not the answer – a huge bid could tempt the Bundesliga side
8/10 Marco Reus - Various
One of the world’s best young players, Reus is being linked with just about every major European club. Manchester United and Liverpool appear to be leading the race in England, but Bayern Munich, Real Madrid and several other clubs would be delighted with the youngster. Reus’ cheap release clause, the cause of all the speculation, doesn’t take effect until next summer, so a big bid may tempt Dortmund to sell now
9/10 Victor Valdes - Liverpool
The former Barcelona goalkeeper is looking for a new club as he continues his recovery from a serious knee injury that forced him out of the World Cup. Liverpool are looking for a new goalkeeper after letting go of Pepe Reina, and Valdes would certainly provide competition for No 1 Simon Mignolet should he regain full fitness.
10/10 Danny Welbeck - Arsenal/Tottenham
The England international is a target for a number of Premier League clubs, but Manchester United are reluctant to strengthen a potential top-four rival with his departure. As a result, any destination will have to cough up a £5m just to take him on loan, while a permanent deal could be largely inflated given his homegrown status.
Barcelona have confirmed they will take the case to the Court of Arbitration for Sport.
The Spanish club are free to continue signing players during the current window whilst CAS looks into the case.
Fifa's statement added: "Barcelona is to serve a transfer ban which will see the club prevented from registering any players at both national and international level for two complete and consecutive transfer periods, starting with the next registration period (January 2015) given that the appeal of the club had been granted suspensive effect by the chairman of the FIFA appeal committee.
"FC Barcelona has also been ordered to pay a fine of CHF 450,000 (£295,000) and been given a period of 90 days from today in which to regularise the situation of all minor players concerned."
Barcelona were found guilty of breaching Fifa's rules on the transfer of players aged under 18.
The players in question were registered and participated in competitions with the Catalan club between 2009 and 2013, while the Spanish Football Federation (RFEF) was also sanctioned by Fifa for the same breaches.
The RFEF also saw its appeal turned down on Wednesday and has been fined.
Fifa's statement added: "The RFEF has been ordered to pay a fine of CHF 500,000 (£330,000) and granted a period of one year in which to regularise their regulatory framework and existing system concerning the international transfer of minors in football."