Cardiff will allow long-serving Kevin McNaughton to leave this summer along with Danny Gabbidon and Nicky Maynard.
Highly-rated Atletico Madrid midfielder Saul Niguez has signed a new five-year contract.
Lionel Messi has agreed a new contract to keep him at Barcelona until 2018.
The Catalan giants confirmed on their official website the Argentinian would pen the deal "in the coming weeks".
Barca also revealed Xavi and Carles Puyol had agreed extensions until 2016.
Messi's current deal runs until June 2016 and the new agreement will keep him at the Nou Camp beyond his 31st birthday.
The forward has enjoyed an extraordinary year, even by his own remarkable standards, netting his 89th and 90th goals of 2012 at the weekend.
The 25-year-old had already surpassed Gerd Muller's 40-year-old record of 85 goals in a calendar year.
He is also in contention to claim a fourth successive FIFA Ballon d'Or crown, being named on a three-man shortlist alongside Cristiano Ronaldo and team-mate Andres Iniesta.
Lionel Messi factfile:
1987: June 24 - Born in Rosario, Santa Fe, Argentina.
1995: Joins Newell's Old Boys.
1998: Diagnosed with a growth hormone deficiency at age of 11.
2000: Moves to Barcelona, aged 13.
2003: November 16 - Makes first-team debut in friendly at Porto at the age of 16.
2004: October 16 - Appears in first official Barca match, aged 17, in 1-0 derby win at Espanyol.
2005: May 1 - Becomes youngest player to score for Barcelona by netting against Albacete.
June - Helps Argentina to World Youth Championship triumph in Holland. Messi is competition's top scorer and is named player of the tournament.
August 17 - Makes full Argentina debut as second-half substitute in Hungary, only to be shown a red card within two minutes.
2006: May - Helps Barca retain Primera Division title and win Champions League, although he misses out on Champions League final win over Arsenal in Paris due to injury.
June 16 - Becomes youngest player to represent Argentina at a World Cup with substitute appearance against Serbia & Montenegro. Also nets final goal in 6-0 win to become fifth youngest goalscorer in World Cup history.
2007: July - Named young player of the tournament after helping Argentina to Copa America final, where they lose to Brazil.
December 2 - Finishes third behind Kaka and Cristiano Ronaldo in Ballon d'Or voting.
2008: July 3 - Included in Argentina squad for Olympic Games in Beijing, prompting protracted dispute between the Argentinian federation and Barcelona, who want the player available for Champions League qualifiers.
August 7 - Barca announce they will allow Messi to remain with Argentina squad for the duration of the Olympics.
August 23 - Helps Argentina to gold with a 1-0 victory over Nigeria in the final in Beijing's Bird's Nest stadium.
2009: May 27 - Scores second goal as Barcelona beat Manchester United 2-0 to win Champions League final in Rome. Also helps Barca win the Primera Division and Copa del Rey titles in an unprecedented treble.
December 1: Wins Ballon d'Or.
2010: May - Equals Ronaldo's club record of 34 goals in a league season as Barca win the Primera Division title again.
November 20 - Second hat-trick of the season in Barca's 8-0 win over Almeria takes him to 100 goals in La Liga.
2011: January 10 - Wins Ballon d'Or.
May: Finishes the season with 50 goals in league, Copa del Rey and Champions League action.
August - Named Argentina captain by new coach Alejandro Sabella.
December - Part of the Barcelona squad which wins the Club World Cup in Japan.
2012: January 9 - Retains Ballon d'Or prize.
March 7 - Becomes first man to score five times in a Champions League game as Barca crush Bayer Leverkusen 7-1.
March 20 - Becomes Barcelona's all-time leading goalscorer, with 233, after scoring twice in the Primera Division match with Granada.
May 25 - Scores Barca's second in a 3-0 Copa del Rey final win over Athletic Bilbao in Madrid.
December 9 - Breaks Gerd Muller's record of 85 goals in a calendar year with his 85th and 86th strikes of a remarkable 2012 in Barcelona's win at Real Betis.
December 18 - Agrees new contract to keep him at Barcelona until 2018.