Real Oviedo, once a top team, has gradually lost its luster amid deep financial and labor troubles. They last played in the top flight in 2001 and are now down in the regional Segunda B (third tier) and are currently fourth, five points behind leaders Tenerife.

Many individual investors have responded to the club's appeal for cash in recent weeks. Real Madrid club invested earlier this month some $127,100 to help its Asturian rival keep afloat.

"We are at around 35 percent (stake) which makes us, by far, the top holder," Slim's spokesman and chief aide Arturo Elias Ayub told Reuters on Saturday.

He said additional investments in the Spanish team were being received until midnight Saturday.

The investment in the Real Oviedo was made via Slim's privately held Inmobiliaria Carso.

The team "has a lot of qualities, has an impressive history, a strong following," Elias Ayub added. "More than a business investment, it was a personal investment (for Slim), a support to the team's fans."

Slim, who owns telecommunications, infrastructure, retail, mining and banking businesses, tapped the sports world in September after his mobile phone giant, America Movil (AMXL.MX) (AMX.N), bought a 30 percent stake in the Leon and Pachuca clubs in Mexico's first division for an undisclosed amount.

America Movil also bought the transmission rights for the Leon team and the club's matches are now aired with Fox Sports on cable networks across Latin America, Telemundo in the United States and via popular sports online site Medio Tiempo.

Elias Ayub said that the Real Oviedo purchase could bring new transmission opportunities to Slim's webstreaming effort, UnoTV, which the tycoon has used to bypass a Mexican government ban that forbids him from offering broadcast television.

The acquisition will also allow exchanges of players between Slim's Mexican teams and the Spanish club, Elias Ayub said.

The Leon and Pachuca purchases by Slim, who is an avid sports fan, challenged the grip that top broadcasters Televisa (TLVACPO.MX) (TV.N) and TV Azteca (AZTECACPO.MX) have held on the Mexican soccer business for years.

Themselves owners of big money-making professional soccer franchises, the broadcasters have been often accused by smaller teams of setting the rules in terms of transmission rights and advertising.

Slim, who has been fighting for years to get a television license, took the TV networks by surprise last year by webstreaming free live coverage of the Pan American Games, which the stations said was a breach of their broadcast rights.

The tycoon dominates the fixed-line, cell phone and Internet markets in Mexico and operates telecom businesses in 16 other Latin American countries plus the United States.

Slim embarked this year on his first European telecom expansion after buying stakes in Dutch and Austrian companies.

(Additional reporting by Veronica Gomez in Mexico and Iain Rogers in Madrid; Editing by Eric Walsh)

• A Permanent Economic Emergency