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 left this month without a job to go to.
It is understood that Citigate Dewe Rogerson 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.