We report on magnetization data obtained as a function of temperature and magnetic field inLi2(Pd0.8Pt0.2)3B andLi2Pd3B non-centro-symmetric superconductors. Reversible magnetization curves were plotted asM1/2 versusT. This allows study of the asymptotic behavior of the averaged orderparameter amplitude (gap) near the superconducting transition. Results ofthe analysis show, as expected, a mean field superconducting transition forLi2Pd3B. By contrast, a large deviation from the mean field behavior is revealed forLi2(Pd0.8Pt0.2)3B. This is interpreted as due to the strength of the non-s-wave spin-tripletpairing in this Pt-containing compound which produces nodes in the orderparameter and, consequently, phase fluctuations. The diamagnetic signal aboveTc(H) inLi2Pd3B is wellexplained by superconducting Gaussian fluctuations and agrees with the observed mean field transition. ForLi2(Pd0.8Pt0.2)3B the diamagneticsignal above Tc(H) is much higher than the expected Gaussian values and appears to be well explained bythree-dimensional critical fluctuations of the lowest-Landau-level type, which somehowagrees with the scenario of a phase mediated transition.