  We aim to estimate and analyse the physical properties of the infrared
counterparts of HMPOs by comparing their spectral energy distributions (SED)
with those predicted by radiative transfer accretion models of YSOs. The SED of
68 IRCs are extended beyond the GLIMPSE photometry to the possible limits, from
the near-infrared to the millimetre wavelengths by using the 2MASS, GLIMPSE
version 2.0 catalogs, MSX, IRAS and some single dish (and interferometric)
(sub)mm data. An online SED fitting tool that uses 2D radiative transfer
accretion models of YSOs is employed to fit the observed SED to obtain various
physical parameters. The SED of IRCs were fitted by models of massive
protostars with a range of masses between 5-42 Msun and ages between 10^3 and
10^6 years. The median mass and age are 10 Msun and 10^4 yrs. The envelopes are
large with a mean size of ~ 0.2-0.3 pc and show a distribution that is very
similar to the distribution of the sizes of 8 micron nebulae discussed in Paper
I. The estimated envelope accretion rates are high with a mean value of 10^(-3)
Msun/yr and show a power law dependence to mass with an exponent of 2,
suggesting spherical accretion at those scales. Disks are found to exist in
most of the sources with a mean mass of 10^(-1.4+-0.7) Msun. The observed
infrared-millimetre SED of the infrared counterparts of HMPOs are successfully
explained with an YSO accretion model. The modelled sources mostly represent
proto-B stars although some of them could become O stars in future. We
demonstrate that many of these results may represent a realistic picture of
massive star formation, despite some of the results which may be an effect of
the assumptions within the models.
