The FTSE 100 security giant, formerly known as Group 4 Securicor, has used Citigate Dewe Rogerson to support its comms efforts since 2003.
The agency currently handles G4S's financial PR for both financial calendar and M&A related work, b2b comms for UK units, crisis and issues work, and runs a 24-hour, 365-days-a-year press office.
Debbie McGrath, group comms director at G4S, confirmed a pitch process was under way, but declined to provide details about the brief. However, she did confirm the account included the work Citigate currently undertakes and some other broader aspects.
The firm has operations in more than 120 countries, but the brief is believed to be primarily UK-based, with only aspects of international work.
The process is still in the relatively early stages, but it is thought a longlist of agencies to be invited to pitch has already been finalised.
Citigate is understood to be repitching, along with a significant number of top financial and corporate comms players.
G4S, created by the 2004 merger of Group 4 Falck with Securicor, has grown from its roots in traditional security to provide a host of security-related services across the globe. The company's work ranges from protecting nuclear and energy facilities, to running prisons and providing security for public events and concerts.
G4S has about 625,000 staff across the world, servicing clients including governments, financial institutions and private companies.
The only other agency currently retained by G4S is FastTrack, part of Chime Communications, which supports the group's sports sponsorship programme and remains unaffected.