  Charged particles, generated in solar flares, sometimes can get extremely
high energy, above the 500 MeV level, and produce abrupt ground level
enhancements (GLEs) on the ground-based detectors of cosmic rays. The initial
flares are strong eruptions and they should be originated from active regions
(ARs). A list of GLE events and associated flares was initially available, and
our aim here was to find the hosting AR for each GLE event. Moreover, we aimed
to classify the revealed ARs using the magneto-morphological classification
(MMC: \citealp{2021MNRAS.507.3698A}). We have shown that in 94\% of cases such
ARs belong to the most complex morphological classes, namely, $\beta \gamma$,
$\beta \delta$, $\gamma \delta$, $\beta \gamma \delta$ classes by the Hale
classification and B2, B3 classes by the MMC. We also found that the
GLE-associated ARs are the ARs with the total unsigned magnetic flux much
stronger than the common ARs of the same complexity. The set of GLE-related ARs
only partially overlaps with the set of SARs (super-active regions). These ARs
seem to be a manifestation of nonlinearities in the regular process of the
global mean-field dynamo, the key ingredient to keep fluctuations and to create
critical conditions in different aspects of the solar activity.
