The energy provider reappointed Blue Rubicon in 2012 as its retained comms agency, to manage corporate and consumer PR. The agency had first won the account in 2007.
Several agencies have told PRWeek that they have sent credentials to the energy company and are going to pitch for the account.
Tim Cowen, head of media relations at British Gas, declined to comment on the tender but said: "Blue Rubicon is our agency, nothing has changed. We are continuing to work with it."
Last year British Gas brought in Kaper for a six-figure brief focusing on Generation Green, a programme linking up with schools nationwide to educate children on the issues of energy and sustainability.
The shift of the work from Blue Rubicon, which repitched for the account, did not affect its role as lead agency handling the energy giant’s consumer and corporate PR.