  Fast radio bursts (FRB) are enigmatic powerful single radio pulses with
durations of several milliseconds and high brightness temperatures suggesting
coherent emission mechanism. For the time being a number of extragalactic FRBs
have been detected in the high-frequency radio band including repeating ones.
The most plausible explanation for these phenomena is magnetar hyperflares. The
first observational evidence of this scenario was obtained in April 2020 when
an FRB was detected from the direction of the Galactic magnetar and soft gamma
repeater SGR1935+2154. The FRB was preceded with a number of soft gamma-ray
bursts observed by Swift-BAT satellite, which triggered the follow-up program
of the H.E.S.S. imaging atmospheric Cherenkov telescopes (IACTs). H.E.S.S. has
observed SGR1935+2154 over a 2 hour window few hours prior to the FRB detection
by STARE2 and CHIME. The observations overlapped with other X-ray bursts from
the magnetar detected by INTEGRAL and Swift-BAT, thus providing first
observations of a magnetar in a flaring state in the very-high energy domain.
We present the analysis of these observations, discuss the obtained results and
prospects of the H.E.S.S. follow-up program for soft gamma repeaters and
anomalous X-ray pulsars.
