A non-analyticity of the Fourier components, $\tilde{V}^{vv}(k)$, of the inherently anisotropic, long-range and quasi-oscillating ‘strain-induced’ $v$—$v$-interaction energies, $V^{vv}(r)$, dependent on distances {$r$} between vacancies in their solid solution based on finite b.c.c. crystal (for example, b.c.c.-Mo, Nb, W) is considered with regard for its discrete structure and elastic anisotropy. Interactions of point defects are studied by means of the lattice statics method within the scope of the quasi-harmonic approximation. The numerical and analytical calculations of energy parameters for ‘strain-induced’ and ‘electrochemical’ interactions of vacancies within the b.c.c. crystal (for example, b.c.c.-Mo, Nb, W) are carried out. Their behaviour near and far from the centre of the b.c.c.-lattice reciprocal-space Brillouin zone (particularly, on its surface) is studied. Within the long-wave approximation ($k \cong 0$), anisotropic expansion coefficients, $A^{vv}(n)$, $B^{vv}(n)$, for the Fourier components, $Q^{vv} + A^{vv}(n) + B^{vv}(n)k^{2}$ ($n \equiv k/k$), of the ‘strain-induced’ $v$—$v$ interaction energies near the centre ($k = 0$) of Brillouin zone are defined, in particular, depending on the elasticity modules of b.c.c. crystal. As revealed, $B^{vv}(n) \geq 0$ along the high-symmetry [100], [110], [111] directions in reciprocal space for b.c.c. crystal (irrespective of its elastic-anisotropy factor sign), and as always, $V^{vv}(0) < Q^{vv} + A^{vv}(n)$.