  We study the category of finite--dimensional bi--graded representations of
toroidal current algebras associated to finite--dimensional complex simple Lie
algebras. Using the theory of graded representations for current algebras, we
construct in different ways objects in that category and prove them to be
isomorphic. As a consequence we obtain generators and relations for certain
types of fusion products including the $N$--fold fusion product of
$V(\lambda)$. This result shows that the fusion product of these types is
independent of the chosen parameters, proving a special case of a conjecture by
Feigin and Loktev. Moreover, we prove a conjecture by Chari, Fourier and Sagaki
on truncated Weyl modules for certain classes of dominant integral weights and
show that they are realizable as fusion products. In the last section we
consider the case $\mathfrak{g}=\mathfrak{sl}_2$ and compute a PBW type basis
for truncated Weyl modules of the associated current algebra.
