1. Is there a ban on donations from foreign interests to political parties?

(2) The parties are not authorized to accept donations:[…]
3. Donations from outside the scope of this law unless […]
c) it is a donation from a foreigner of not more than EUR 1,000;[…]
Source: § 25(2), Political Parties Act, 1967 (amended 2018)

There is no ban on donations from foreign interests to political parties. However, donations are limited to EUR 1,000.