FIFA, which approved the use of technology to see if a ball has crossed the goal-line last year following a number of controversial incidents, said earlier that a fourth system has been granted a licence.
"It must not be a secret," Blatter told reporters.
"Now we have the technology and it shows if it's a goal or not a goal we have to be transparent, or else there is no reason to do it.
"It is something we need in football. I don't want to go back into the history of it... but now we have four systems and not to use it would be foolish."
"The broadcasters need to have that accessibility and to show the goal-line incident which is at the heart of the integrity of the decision that has to be made," he said.
"Whether you show it in the stadiums or not is a decision not yet been made because for me, that falls in the 'controversial decision' element.
"There might be a very good reason to show it but we don't show controversial incidents in Premier League matches on the big screens, and some decisions may fall into that category."
IFAB, which comprises officials from the four British associations as well as four members from world governing body FIFA and is the game's ultimate law-making body, will also consider changes to the offside rule this weekend.
Fans, pundits and teams have called for clarity on when players are "active".
FIFA is proposing that a player should be considered offside when "gaining an advantage by being in that position", including when receiving the ball from a rebound or deflection from the goal frame or when a player in the defending team attempts a tackle, block or save.
IFAB will is also considering changing the law's wording on uncontested dropped balls to ensure that a goal cannot be allowed if one team expecting to receive the ball after an uncontested drop ball, following an injury to an opponent for example, has not touched it.
