Saw, who had been at Citigate for almost a decade, is thought to have left earlier this month to work as an independent corporate reputation professional.
She joined the City PR firm in 2002 from Burson-Marsteller, where she was MD, brands & technology. She has also worked as an MD at Fleishman-Hillard.
Saw could not be reached for comment at the time of going to press.
Her departure comes two months after former Citigate chief executive Jonathan Clare left the agency.
In late September, it emerged that Clare had teamed up with fellow Citigate co-founder David Wright and become executive chairman of newly launched Newgate Public Relations.
It is thought that Saw may also end up at Newgate, along with former Citigate MD of public affairs Simon Nayyar, who also left in October without a job to go to.
Citigate’s corporate practice will continue to be led by MD Jonathan Flint.
The agency has lost a number of senior practioners in recent months, including George Cazonove to Tullow Oil, Lucie Holloway to the London Stock Exchange and Sarah Gestetner to private equity firm Warburg Pincus.
It is understood that Citigate is looking for a number of new hires and has recruited senior individuals, including directors Caroline Merrell from Cubitt Consulting to its financial division, and Heather Forty from Skywrite PR to the corporate team.