Apple chief Tim Cook and Google chairman Eric Schmidt are expected to face questioning in a lawsuit accusing Silicon Valley giants of secretly agreeing not to "poach" one another's workers, according to officials and court documents.

Plaintiffs' attorneys said US District Court Judge Lucy Koh endorsed questioning Cook, Schmidt, as well as Intel head Paul Otellini, after reasoning that high-level executives would know about restrictions on hiring talent.

During a hearing Thursday in her courtroom in the California city of San Jose, Koh referred repeatedly to email evidence that included a request in 2007 by then Apple chief Steve Jobs that Google stop recruiting Apple workers.

While Cook was not mentioned in the email messages, it was reasonable to expect that his position as chief operating officer included being kept apprised of issues involving employee expenses, the judge said.

Cook took over as Apple chief in 2011 after Jobs stepped down due to a battle with cancer, which claimed his life.

Schmidt was scheduled for deposition on February 21, while Intuit chief and Apple board member Bill Campbell was slated to be deposed the fifth of that month, according to court documents. The date of Cook's deposition has not been set.

The lawsuit filed in 2011 accuses a set of technology companies of stifling careers and earnings prospects of employees by agreeing not to "poach" one another's workers.

Lawyers representing the plaintiffs have asked Koh to grant them class-action status to represent all workers who may have been affected. A jury trial is set to begin in November.

"We're pressing forward to comply with the court schedule and get the case ready for trial in November," said plaintiffs' attorney Brendan Glackin of the Lieff Cabraser law firm in San Francisco.

The civil suit followed the settling of restraint of trade litigation by the US Justice Department due to the "no-poaching" agreement.