(Reuters) - Molson Coors Brewing Co (TAP.N) and Corona beer brewer Grupo Modelo SAB de CV (GMODELOC.MX) have been exploring a joint bid for Australia's Foster's Group Ltd (FGL.AX), a source familiar with the situation said on Thursday. Banks including Bank of America Corp (BAC.N) and Deutsche Bank AG (DBKGn.DE) are helping the beer companies to come up with financing for a possible bid, the source said, declining to be named because the talks are not public.