Finite-size correction to the pionium lifetime due to ω and η' contributions

It is shown that for pNi interactions at 24 GeV/c, the fractions of the pi+/-omegapi and pairs with one pion from the omega and eta' decays, respectively, at small values of the relative momentum Q < = 4 MeV/c of pions in the c.m. system of the pi+pi- pair are fomega = 0.150 +/- 0.019 and. With these values of fomega and, the uncertainty in the pionium breakup probability and the corresponding overestimation of the pionium lifetime in the DIRAC experiment at CERN are DeltaPbr/Pbr = (3.0 +/- 1.0)% and Deltatau/tau = (7.8 +/- 2.6)%.