A sample of 1.69imes107 fully reconstructed pi0ogammae+e−
decay candidates collected by the NA48/2 experiment at CERN in 2003--2004 is
analysed to search for the dark photon (A′) production in the pi0ogammaA′ decay followed by the prompt A′oe+e− decay. No signal is observed,
and an exclusion region in the plane of the dark photon mass mA′​ and
mixing parameter arepsilon2 is established. The obtained upper limits on
arepsilon2 are more stringent than the previous limits in the mass range
9~
m MeV/c^2<70~
m MeV/c^2. The NA48/2 sensitivity to the dark
photon production in the KpmopipmA′ decay is also evaluated