  A finitely generated group $G$ acting on a tree with infinite cyclic edge and
vertex stabilizers is called a generalized Baumslag--Solitar group ($GBS$
group). We prove that a 1-knot group $G$ is $GBS$ group iff $G$ is a torus-knot
group and describe all n-knot GBS groups for $n\geqslant 3$.
