(Reuters) - A U.S. judge on Thursday said she had concerns about approving a $324.5 million settlement involving Apple, Google and two other tech companies in a lawsuit accusing them of conspiring to avoid poaching each other's workers.

Tech employees filed a class action lawsuit against Apple Inc, Google Inc, Intel Inc and Adobe Systems Inc in 2011, alleging they conspired to refrain from soliciting one another's employees to avert a salary war.

The case has been closely watched due to the potentially high damages award and the opportunity to peek into the world of Silicon Valley's elite. The four companies agreed to settle with the plaintiffs in April for a total of $324.5 million. The plaintiffs had planned to ask for about $3 billion in damages at trial, which could have tripled to $9 billion under antitrust law.

U.S. District Judge Lucy Koh in San Jose, California must approve the deal. At a court hearing on Thursday, Koh said the plaintiffs had leverage going into trial against the defendants, given the strength of the evidence in the case. Several emails showed Apple's late co-founder Steve Jobs, former Google CEO Eric Schmidt and some of their Silicon Valley rivals hatching plans to enforce their no-poaching agreement.

"I just have concerns about whether this is really fair to the class," Koh said, adding that she had not made a decision about whether to approve the deal.

Plaintiff attorney Kelly Dermody said the workers faced serious risks on appeal had the case gone forward, especially since the U.S. Supreme Court has been skeptical of large class action lawsuits.

"Those are very, very real risks for plaintiffs," Dermody said.

One of the four named plaintiffs, Michael Devine, filed an objection saying the settlement let the companies off too easily. Workers would receive a few thousand dollars each on average.

However, attorneys for plaintiffs argued in court papers that Devine's objection should not doom what they consider a fair and reasonable settlement.