Barcelona was banned by FIFA from signing any players for next season after being found guilty on Wednesday of repeatedly breaching transfer regulations.
Club officials said they would appeal the heavy sanction, which covers the summer and January transfer windows and followed an investigation into the Spanish champions' signing of players under the age of 18 from 2009-13.
FIFA carried out an investigation last year and found the club as well as the Spanish football federation (RFEF) guilty of several violations in relation to rules governing international transfers and registering foreign players.
The world governing body did not explicitly state when the punishment was due to start, but if imposed immediately it would prevent Barca from making signings in summer 2014 or winter 2015.
A FIFA statement read: "The FIFA Disciplinary Committee has sanctioned the Real Federacion Espanola de Futbol (RFEF) and Spanish club FC Barcelona for breaches relating to the international transfer and registration of players under the age of 18.
"The investigations concerned several minor players who were registered and participated in competitions with the club over various periods between 2009 and 2013."
FIFA only permits international youth transfers when one of the three following situations apply: The player's parents have moved to another country for non-related reasons; The move takes place within the European Union if a player is aged between 16 and 18; The player's home is less than 50 kilometres from the national border being crossed.
The FIFA statement added: "FC Barcelona has been found to be in breach of art. 19 of the Regulations in the case of 10 minor players and to have committed several other concurrent infringements in the context of other players, including under Annexe 2 of the Regulations.
"The Disciplinary Committee regarded the infringements as serious and decided to sanction the club with a transfer ban at both national and international level for two complete and consecutive transfer periods, together with a fine of CHF 450,000 [$508,000 or 368,000 euros]. Additionally, the club was granted a period of 90 days in which to regularise the situation of all minor players concerned."
In February 2013, FIFA found that Barca had regularly failed to comply with its transfer regulations and extended a ban to cover six players from Barca's Cadete and Juvenil youth teams. This meant that South Koreans Lee Seung-Woo, Jang Gyeolhee and Paik Seung-Ho, French youngster Theo Chendri, Nigerian-Dutch player Bobby Adekanye and Cameroonian Patrice Sousia were training with their teams but unable to play in competitive games.
FIFA president Sepp Blatter backed the move at the time, saying: "The Barca case will be studied by FIFA's Players' Status Committee, but the rules for the signing of minors are very clear."
Despite Wednesday's ruling, a Barca spokesperson has told AS the club do not expect the ban to come into force this summer.
"We are relaxed," the spokesperson said. "It is a habitual process in which we have 90 days to explain how we signed these players.
"It would not be two years of sanctions. It would be two transfer windows."
El Pais reported on Wednesday that club sources have indicated that they will appeal at the Court of Arbitration for Sport, using Chelsea's successful appeal of a ban relating to the Gael Kakuta transfer from Lens as a precedent.
If the punishment is enforced this summer, the ruling could pose serious problems for Barcelona, who are also still contending with the ongoing investigation by a Spanish judge into irregularities in last summer's signing of Neymar.
Given that both Barcelona's senior goalkeepers, Victor Valdes and Jose Manuel Pinto, are out of contract this summer, the club had been expected to sign at least one replacement, with Borussia Moenchengladbach's Marc Andre ter Stegen rumoured to have already agreed to a move. It has already been suggested that Valdes could yet stay on, but he has been ruled out for the next seven months through injury.
It was also announced last month that captain Carles Puyol would leave at the end of the season and Barca were expected to reinforce their defence, while club president Josep Maria Bartomeu has spoken recently of having 120 million euros to spend in a major squad reorganisation ahead of the 2014-15 campaign.
The reigning Spanish champions last week announced that Croatian youngster Alen Halilovic was due to move to the Camp Nou in the summer after a deal was agreed with Dinamo Zagreb.