  The inclusive charged particle transverse momentum distribution is measured
in proton-proton collisions at $\sqrt{s} = 900$ GeV at the LHC using the ALICE
detector. The measurement is performed in the central pseudorapidity region
$(|\eta|<0.8)$ over the transverse momentum range $0.15<p_{\rm T}<10$ GeV/$c$.
The correlation between transverse momentum and particle multiplicity is also
studied. Results are presented for inelastic (INEL) and non-single-diffractive
(NSD) events. The average transverse momentum for $|\eta|<0.8$ is $\left<p_{\rm
T}\right>_{\rm INEL}=0.483\pm0.001$ (stat.) $\pm0.007$ (syst.) GeV/$c$ and
$\left<p_{\rm T}\right>_{\rm NSD}=0.489\pm0.001$ (stat.) $\pm0.007$ (syst.)
GeV/$c$, respectively. The data exhibit a slightly larger $\left<p_{\rm
T}\right>$ than measurements in wider pseudorapidity intervals. The results are
compared to simulations with the Monte Carlo event generators PYTHIA and
PHOJET.
