Is it possible to buy or sell non-residential real estate during martial law by power of attorney?

Yes, but only under certain conditions.

The power of attorney for a contract of sale must be issued no later than 1 month before the date of the agreement or 2 months if such power of attorney is certified by a consular institution.

If the power of attorney is issued later, it is necessary to additionally receive a notarized statement confirming the power of attorney from the principal.