The delayed annihilation of antiprotons, which was recently discovered in liquid $^{4}\mathrm{He}$ at KEK, has been studied at CERN in gas-phase $^{4}\mathrm{He}$ and $^{3}\mathrm{He}$. The annihilation time spectra in gaseous $^{4}\mathrm{He}$ at various pressures were found to be similar to that for liquid $^{4}\mathrm{He}$. The observed average lifetime in the region tg1 \ensuremath{\mu}sec for 3 atm $^{4}\mathrm{He}$ was about 3.2 \ensuremath{\mu}sec, while for 3 atm $^{3}\mathrm{He}$ gas it was 2.8 \ensuremath{\mu}sec, i.e., shorter by 15%. The time spectra show a growth-decay-type function, which is indicative of the presence of a series of metastable states. For $^{4}\mathrm{He}$ and $^{3}\mathrm{He}$ they have nearly identical shapes, differing only in the time scale by (14 \ifmmode\pm\else\textpm\fi{}3)%. These observations are qualitatively consistent with the atomic model of p\ifmmode\bar\else\textasciimacron\fi{}${\mathit{e}}^{\mathrm{\ensuremath{-}}}$${\mathrm{He}}^{2+}$ proposed by Condo [Phys. Lett. 9, 65 (1964)]. The time spectra were found to be sensitive to the presence of small amounts (as small as 20 ppm) of ${\mathrm{H}}_{2}$. No evidence was seen for delayed annihilation in gaseous Ne.