  We study phase transitions in uniformly frustrated SU(N)-symmetric
$(2+\epsilon)$-dimensional lattice models describing type-II superconductors
near the upper critical magnetic field $H_{c2}(T)$. The low-temperature
renormalization-group approach is employed for calculating the beta-function
$\beta(T,f)$ with $f$ an arbitrary rational magnetic frustration. The
phase-boundary line $H_{c2}(T)$ is the ultraviolet-stable fixed point found
from the equation $\beta(T,f)=0$, the corresponding critical exponents being
identical to those of the non-frustrated continuum system. The critical
properties of the SU(N)-symmetric complex Ginzburg-Landau (GL) model are then
examined in $(4+\epsilon)$ dimensions. The possibility of a continuous phase
transition into the mixed state in such a model is suggested.
