Extra punishment for shirt messages
Players at this summer's World Cup face FIFA disciplinary action for revealing any slogan or image on shirts underneath their official kit.
Football's rule-making panel modified the law, which previously related only to political and religious statements and advertising, and agreed on Saturday it will take effect on June 1.
The panel, known as the International FA Board (IFAB), said breaking the rule was not a yellow-card offence, though players can be later disciplined by competition organisers.
"We think it's the simplest rule for the image of the game to start from the basis that there is no room for slogans, images or alternative sponsor logos on the undershirt," said IFAB member Alex Horne, general secretary of England's FA.
At the 2010 World Cup final, Spain midfielder Andres Iniesta scored the winning goal then took off his shirt to reveal a statement dedicated to Spanish player Dani Jarque who died that season. A similar act will now lead to a probable FIFA fine in addition to a yellow card for removing the shirt.
Also, IFAB approved head coverings for male and female players. The final consent for head coverings follows extra trials after a July 2012 decision to approve scarves worn by Islamic female players.
Valcke said Saturday's decision extended to male players following a request from Sikh community leaders in Canada.
The tougher rule on personal messages follows incidents this season when players including Didier Drogba of Galatasaray revealed tributes to Nelson Mandela on their undershirts.
Italy forward Mario Balotelli famously revealed "Why Always Me?" written on his undershirt in 2011 after scoring for his then-club Manchester City against rivals Manchester United.
Still, the IFAB panel -- comprising FIFA and the four British associations -- agreed the England-proposed amendment would help avoid complications with statements having different meanings in different languages and cultures.
"It is better to say no and have a clean situation," FIFA secretary general Jerome Valcke said at a briefing after the two-hour IFAB meeting.
Information from The Associated Press was used in this report.