We establish two inequalities of Stein-Weiss type for the Riesz potential operator I α,γ ( B− Riesz potential operator) generated by the Laplace-Bessel differential operator Δ B in the weighted Lebesgue spaces L p,|x| β ,γ . We obtain necessary and sufficient conditions on the parameters for the boundedness of I α,γ from the spaces L p,|x| β ,γ to L q,|x| −λ ,γ , and from the spaces L 1,|x| β ,γ to the weak spaces W L q,|x| −λ ,γ . In the limiting case p = Q/α we prove that the modified B− Riesz potential operator I α,γ is bounded from the spaces L p,|x| β ,γ to the weighted B − BMO spaces BMO |x| −λ ,γ .As applications, we get the boundedness of I α,γ from the weighted B -Besov spaces B s pθ ,|x| β ,γ to the spaces B s qθ ,|x| −λ ,γ . Furthermore, we prove two Sobolev embedding theorems on weighted Lebesgue L p,|x| β ,γ and weighted B -Besov spaces B s pθ ,|x| β ,γ by using the fundamental solution of the B -elliptic equation Δ α/2 B . Mathematics subject classification (2010): 42B20, 42B25, 42B35.