The banking behemoth currently uses Maitland for its UK financial PR, but will incorporate that brief into a wider account.
The move is intended to globalise the bank's message and reinforce its brand across the globe.
HSBC group communcations director Richard Beck said: ‘We have worked hard since taking on global communications for HSBC almost two years ago, to increase HSBC's media contact and profile with considerable support in the UK from the Maitland team.
'It is now time to actively tell HSBC's story, a good one in a difficult market for banks, and to extend our reach to international press in HSBC's key growth markets.'
The firm will be contacting agencies over the coming days to invite them to pitch, with a view to making an appointment early next year.
It is believed in the industry that the substantial retainer will be worth a mid to upper-six figure sum.
The precise nature of the brief has yet to be decided, but HSBC wants a high degree of consistency in its messaging around the world and may require more than one agency.
The brief will be less focussed on specific financial calendar work and will centre on wider messaging and corporate reputation.
The bank feels that its recent communications approach has had to be reactive, given the perilous state of the market and its own troubles in the US, and now wants to get on the front foot.
It is understood that both Maitland and Burson-Marsteller, recent winners of HSBC's public affairs account, will be short-listed.
The bank is also understood to be ready to contact with other City heavy-hitters, like Brunswick, FD and Finsbury, although a source said such agencies would have to ‘work very hard' to demonstrate there is no conflicts where they also serve the bank's rivals.
It is also thought firm will also approach non-finance specific agencies with large global networks such as Edelman, Ogilvy and MS&L.
HSBC operates in 85 global markets and has a major presence in 65 of those.