Facebook chief operating officer Sheryl Sandberg has claimed her company rebuffed Google's attempt to form a pact that would have suppressed engineers' salaries.

According to her written testimony to a US court, obtained and published today by CNBC, Sandberg said she met Google executives who were – it is claimed – keen to stop Facebook from luring Google employees with promises of fatter pay checks.

Sandberg reportedly told the district court in California she declined the request to limit job offers.

These alleged "no poaching" or "no-compete" deals are at the center of an ongoing case in the San Jose court, in which big-name tech firms stand accused of informally colluding to limit the hiring of employees away from rivals.

Such deals were allegedly forged between companies at the highest levels: the agreements forbid the poaching of staff and dissuade employees from jumping ship by quietly fixing salaries across Silicon Valley, it is claimed.

Apple, Google, Intel, Adobe, Intuit, Pixar and Lucasfilm were named in a class-action lawsuit filed in 2011 by disgruntled engineers who alleged that as far back as 2005 the tech giants had, at the urging of Apple cofounder Steve Jobs, agreed to an unofficial set of rules that discouraged the companies from recruiting each others' employees for key positions.

If the case reaches a full trial, jury selection will begin on May 27 with proceedings to take place through the second week of July. ®