SANTA CLARA — After the San Francisco 49ers rallied support for their new stadium by promising to pay for new youth soccer fields, the NFL team isn’t following through with its part of the deal — and taxpayers will be left footing the multimillion dollar bill.

The unlikely turf war between the Niners and Santa Clara’s youth soccer parents has been quickly buzzing around the normally quiet city and centers on the 49ers’ new $1.3 billion Levi’s Stadium and the city’s adjacent state-of-the-art Youth Soccer Park.

The soccer fields are so renowned that they draw teams from as far away as Southern California. But stadium traffic will be so bad that they will be extremely difficult to use during 49ers home games and other big events, conflicting with one-fourth of the Youth Soccer League’s fall season.

Jed York, owner of the 49ers, told the soccer league in a letter two years ago that the team would fund replacement fields. But the team’s front office shocked the soccer league last week by telling them the Niners had abandoned those plans.

“You feel betrayed or lied to,” said Matt Heintz, president of the 1,500-member Santa Clara Youth Soccer League, which had supported the new stadium that voters approved public financing for in 2010. “It sounds like they got what they wanted, they got the stadium built — and pushed us aside, brushed us under the rug.”

The Santa Clara City Council is set to discuss the issue Tuesday night and said the city is now looking into spending $2 million to develop plans for three replacement fields at existing park sites. More money would be needed later to actually build the fields, much to the dismay of soccer parents who long thought the 49ers would fund the fields at no taxpayer cost.

But the city says the new plan doesn’t use general-fund money, which pays for services such as police officers and firefighters. And it will ensure most kids are not displaced when 49ers games and big events temporarily hinder access to the soccer park, which has three turf fields and lights.

“What this means is we will have doubled the number of available soccer fields on nongame or event days,” Mayor Jamie Matthews said in a statement. “It’s an exciting opportunity to rebuild our reputation as ‘the Youth Sports Capitol.’ “

The 49ers wrote back to the soccer group Friday, saying they supported the city’s new effort to find replacement fields and reiterated their longtime promise that soccer leagues would be able to use the fields on game days if they could stomach the traffic. They requested to use the soccer park for parking 20 days a year, which includes 49ers games and other big events.

When confronted with the complaints that the team had broken its promise, the 49ers would only issue a brief statement: “Throughout our partnership with the City of Santa Clara, we have established a track record for developing creative plans that are respectful of our neighbors,” the team said. “We are confident that will once again be the case with these matters.”

The soccer league, which is made up of mostly Santa Clara residents, says taxpayers shouldn’t have to pay for the team’s broken promise. The money for the initial $2 million study will come from city land sale revenues, and it’s not yet known how the actual construction will be funded, or how much it will cost.

The soccer park fields support 2,500 kids in various organized leagues, and the leagues must pay to use them just like it does at other fields.

The January 2012 letter from York followed private conversations the soccer league said it had with the 49ers owner to help get support for a 2010 ballot measure that authorized public funding for the stadium, which opens in August.

But last week one of York’s vice presidents in the front office said in a letter to the soccer league that the local school fields they had looked into upgrading are “no longer available.” It said now the 49ers would only fund replacement fields if the soccer league was willing to give up its prized soccer park to the Niners to use for VIP stadium parking.

It’s not clear how quickly the city replacement fields would be available, what the quality of the surface would be or where they would be located. Other City Council members declined to comment, saying they had been discussing the situation in closed session because it involved real estate negotiations.

The soccer league fears it could be more difficult to draw out-of-town opponents without the lure of the soccer park’s reputation.

“It’s not fair to the kids,” said the soccer league’s vice president, Steve Robertson, who played for the undefeated Santa Clara University team that won a share of the national title in 1989.

The city, meanwhile, is trying to calm down the soccer community.

“We have a great partnership with the 49ers,” Matthews said. “We are working together on the event operations plan, which will take into consideration the needs of the entire community as we move toward opening Levi’s Stadium.”

Contact Mike Rosenberg at 408-920-5705. Follow him at Twitter.com/rosenbergmerc.