Germany's deputy foreign minister said Sunday that Israel has "no excuse" for blocking humanitarian aid from reaching Gaza, on the eve of a conference on humanitarian support for the territory organised by Cairo.

"Israel must ultimately fulfil its commitments to facilitate humanitarian access to Gaza and to provide adequate humanitarian support at all times," German Deputy Foreign Minister Tobias Lindner said in a statement before heading to Cairo.

"There is no excuse. Israel's right to self-defense stops at the limits of international humanitarian law," he added.