  We present the perturbative parts of the structure functions F_2^c and F_L^c
for a gluon target having nonzero transverse momentum squared at order \alpha
_s. The results of the double convolution (with respect to the Bjorken variable
x and the transverse momentum) of the perturbative part and the unintegrated
gluon densities are compared with HERA experimental data for F_2^c and F_L at
low x values and with predictions of other approaches. The contribution from
F_L^c structure function ranges 10\div30% of that of F_2^c at the HERA
kinematical range.
