We report a calculation of relativistic corrections of order m alpha(7) to the Bethe logarithm for the 2(3)S and 2(3)P states of helium-like ions. The calculation is required for improving the accuracy of theoretical energies of helium-like ions and for checking the evaluation of the m alpha(7) effects in helium performed in Patkos et al. (Phys Rev A 103:042809, 2021), where a significant discrepancy with experimental results was found.
The large-Z limit of the relativistic Bethe logarithm is determined numerically, in excellent agreement with the analytical results obtained from the hydrogen theory.