Is there or is there not an international charter stating much of the modern Israeli land is an illegal occupation? It's a simple question. May be you or someone else can answer it on a second attempt.
Hint: use google.
Nope.
There are UN resolutions that claim to state such things.
As far as international charters go - the San Remo Conference granted what essentially was the British Mandate of Palestine as a Homeland for Jews. This same convention granted most of the rest of the Middle East as homelands for various Arabs.
These agreements by the San Remo Conference were upheld by an International Court of Law.
And, the UN Charter, Chapter 8; Article 80 states:
1. Except as may be agreed upon in individual trusteeship agreements, made under Articles 77, 79, and 81, placing each territory under the trusteeship system, and until such agreements have been concluded, nothing in this Chapter shall be construed in or of itself to alter in any manner the rights whatsoever of any states or any peoples or the terms of existing international instruments to which Members of the United Nations may respectively be parties.
2. Paragraph 1 of this Article shall not be interpreted as giving grounds for delay or postponement of the negotiation and conclusion of agreements for placing mandated and other territories under the trusteeship system as provided for in Article 77.
Which, in essence, means that Great Britain violated the San Remo Conference by giving Transjordan to the Hashemites and by suggesting the remaining Mandate be divided between Arabs and Jews.
And, that ALL resolutions by the UN against the JEWISH State of Israel have been illegal.
Of course, these points are all moot anyway as the majority of Israel's neighbors in the Arab world, including the Arabs called Palestinians, do NOT even recognize the existence of the State of Israel and never recognized the so called 1967 borders in the first place.