  A sample of $4.687\times 10^6$ fully reconstructed $K^\pm\to\pi^\pm\pi^0_D$,
$\pi^0_D\to\gamma e^+e^-$ decay candidates in the kinematic range
$m_{ee}>10~{\rm MeV}/c^2$ with a negligible background contamination collected
by the NA48/2 experiment at CERN in 2003-04 is analysed to search for the dark
photon ($A'$) via the decay chain $K^\pm\to\pi^\pm\pi^0$, $\pi^0\to\gamma A'$,
$A'\to e^+e^-$. No signal is observed, and preliminary exclusion limits on
space of dark photon mass $m_A'$ and mixing parameter $\varepsilon^2$ are
reported.
