I did a little more searching and found out, that altgr+space behaviour can be altered with xkb option nbsp. Adding following line to the keyboard InputDevice section in xorg.conf avoids this issue by disabling the nbsp.
Option "XkbOptions" "nbsp:none"
In KDE systems this can be done alternatively by going to System Settigns -> Regional & Language -> Keyboard layout -> Xkb Options, and selecting option "Space key outputs usual space at any level." for "Using space key to input non-breakable space character".
I did a little more searching and found out, that altgr+space behaviour can be altered with xkb option nbsp. Adding following line to the keyboard InputDevice section in xorg.conf avoids this issue by disabling the nbsp.
Option "XkbOptions" "nbsp:none"
In KDE systems this can be done alternatively by going to System Settigns -> Regional & Language -> Keyboard layout -> Xkb Options, and selecting option "Space key outputs usual space at any level." for "Using space key to input non-breakable space character".