"Football must be financed and supported by local communities," said Blatter during his visit to the European Parliament on Monday.
Blatter was invited to meet parliamentarians by Belgian MEP Ivo Belet (EPP-ED), who authored a report on the future of professional football in Europe.
But the FIFA chief faced scepticism from the European Parliament, which rejected this formula earlier this year, arguing that it would introduce discrimination based on nationality.
The Parliament overwhelmingly voted against the 6+5 formula in a resolution adopted on 8 May (518 votes for, 49 against). Instead, MEPs expressed a preference for the 'home-grown' rule crafted by UEFA, the European football governing body, which establishes a quota of locally-trained players at clubs, irrespective of nationality.
Blatter firmly defended the introduction of national quotas, which were originally envisaged as an incentive for clubs to invest in training young local players. "Support for 6+5 is widespread," he contended.
A significant proportion of the football fraternity backs the FIFA decision. Pelé, Franz Beckenbauer, Johann Cruijff, Steven Gerrard and several EU government ministries have subscribed to it.
The national and local identity of clubs would also be improved by the 6+5 rule, Blatter claimed. "At a club like Bayern Munich," he said, "you nowadays need to provide translation into five languages at training: the national identification of the club is lost".
But Blatter's appearance met with mixed reactions from members of the EU legislature, as the emphasis on national identity did not go unnoticed. Spain's Luis Herrero-Tejedor (EPP-ED) criticised Blatter's views, asking why national identity needed boosting at all. "What is wrong with multiple languages and translations at training?," he asked, commenting: "We use more than 20 languages here, and still we are doing a great job."
Blatter also called on the European Union to restrict foreign ownership of clubs. "Something has to be done about these billionaire owners," he said, referring in particular to England, where eight out of twenty Premier League clubs are owned by foreign investors.
"These people arrive, buy the clubs but they can leave at any moment," he said. "That creates a risk of instability for these teams and the competition as a whole. Ideally a way should be found for clubs to be financed by local investors." To buy a club, "you have to prove your link with the area," he suggested.
Blatter said FIFA would not implement a decision such as the 6+5 rule as long as it was not compatible with the law, but he did stress that "laws must change [when] they are in the interest of the sports movement".
