Singh is understood to be rejoining H&K but declined to comment about the new role.
Singh was brought on board in March to launch the Bell Pottinger Health brand, which incorporated existing healthcare agencies De Facto and MC Bio-Communications (PRWeek, 20 March).
The new division was aimed at attracting ethical clients to complement its existing life-science and biotech accounts.
Before joining Bell Pottinger, Singh worked as joint MD of healthcare at Hill & Knowlton.
She left H&K to go on a sabbatical to Antarctica before resurfacing earlier this year at Bell Pottinger. She joined H&K in 2001 and formerly worked for Ketchum London and Stratis KPR in New York.
Singh said: 'I really enjoyed setting up Bell Pottinger Health but have always wanted to work in more specialist healthcare services.'
Bell Pottinger has already signed up healthcare stalwart Tanya Von Ahlefeldt as a director to replace Singh. She joins from Porter Novelli, where she headed up the healthcare division and has been on gardening leave for three months.
Von Ahlefeldt has extensive comms experience in the global and UK healthcare industry from more than 20 years of working in both the public and private sectors.
'I am sure that my broad product communication and in-depth issues and crisis knowledge will help Bell Pottinger Health to continue the rapid growth it has seen this year,' said Von Ahlefeldt.
Von Ahlefeldt joined Porter Novelli last summer from Ruder Finn (PRWeek, 4 July 2007). Porter Novelli said she would not be immediately replaced but director Rebecca Hunt is heading the division since returning from maternity leave.
Von Ahlefeldt was previously director of healthcare at Manning, Selvage & Lee.
Before that she was client services director at Compass Communications and worked as a healthcare content manager at Hutchison 3G - now called 3.