FIFA President Sepp Blatter said he would welcome the use of goal-line technology at the 2014 World Cup in Brazil if a suitable system can be found.
Ten systems failed to meet FIFA's requirements when they were tested last month, but soccer's rule-making body agreed Saturday to extend trials for another year.
"Goal-line technology helps referees," Blatter said after the meeting of the International Football Association board.
Blatter has reversed his opposition to high-tech aids for referees, citing the failure to award a goal to England despite the ball clearly crossing the line in a late-round match against Germany at the 2010 World Cup. He has called it a "blatant ... and immense error."
The goal would have tied the match at 2-2, but Germany went on to win 4-1.
In a bid to eradicate such errors at the 2014 tournament, the International Football Association Board said more tests will take place in games rather than being conducted at FIFA House in Zurich.
A decision on goal-line technology is expected in March 2012. Blatter hopes more technology tests, which will take place in match conditions, will find a system capable of ruling on disputed goals within a second and provide accuracy.
"We will go on with the technical experiments and then to bring back this item to the IFAB meeting next year in London, and then a final decision will be taken," Blatter said. "If it works definitely, the board will say yes to the technology. And if the board says yes, then there is a no problem, then there should be no problem to have it in 2014.
"I have to restrict my natural optimism and come a little bit back because the tests we have had so far are not conclusive."
The English Football Association, which holds one of the eight IFAB votes, was unhappy that the testing was only extended.
"It's not perfect because we wanted to get the principle of goal-line technology adopted," said Alex Horne, the FA general secretary. "Given where we were last year, when it got thrown out, that was my worst fear that it would happen again.
"My preferred position was we accept the principle and wait for the technology to prove itself. We are now in the position where they want to look at the technology in different environments and then we will make a decision in March next year. That's why next year's meeting will be so important."
The IFAB has approved the use of two additional referees' assistants at the 2012 European Championship in Poland and Ukraine following successful tests based on UEFA President Michel Platini's five-official system in the Europa League.
The five-official system could also be used at the World Cup, Blatter said.
"It is with a lot of optimism that we will have additional referees for 2014," Blatter said.
In a ruling that will displease some soccer teams that play in cold conditions, IFAB banned players from wearing neck-warming snoods. The ban takes effect immediately.
"There was not even a discussion because this is not part of the uniform and it can be dangerous," Blatter said.
The IFAB also decided to approve experiments in South America for referees to use vanishing spray to mark where defensive walls stand.
In another change from July, referees were told to stop play if a stray object, including an extra ball or animal, appear on the pitch. In 2009, Darren Bent scored for Sunderland against Liverpool when the ball deflected in off a beach ball.
IFAB is a 125-year-old body comprising officials from England, Northern Ireland, Scotland and Wales, plus FIFA representing the other 204 soccer nations and referees, coaches and players worldwide.
Each British member has one vote, FIFA has four and a proposed new rule needs six votes to be passed.