From commenter Yitzhak:
There is an interesting aspect of Abbas' demand that there be a 'halt' to what he terms the construction of 'settlements'. The word 'settlement' itself is carefully chosen to convey the sense of illegality and illegitimacy which Abbas desires to associate with Jewish presence in a land that has quite literally been Jewish for millenia, and which was Arab for nineteen years - and even then, only because of a crime against international law committed by the Jordanians in 1948.
Much more insidious, however, is Abbas's demand that Israel not build in these areas. The very act of making such a demand constitutes a violation of the Oslo Accords, or more precisely of the Interim Agreements between the Israelis and the Arabs, signed and witnessed by the European Union, Egypt, Jordan, Russia, and Norway, and of course by the United States, on 28 September 1995 (see Article XVII, para. 1). See inter alia annex to UN document A/48/486-S/26560 dated 11 October 1993.
If you consult the above documentation, in particular Article 27 of Annex III (Civil Affairs Annex), you will note that full rights for construction powers are granted to the respective authorities (in this case, the Israeli Government, and the 'PA' or 'Palestinian Authority'). Judea & Samaria were split into three zones: A, B and C. In Zone A, all control (including security) was handed over to the PA. In Zone B, all control except security, was handed over to the PA. Only in Zone C - which includes Israeli villages and Israeli military installations, was full control retained by the Israeli authorities. In all of these zones (including C), the situation was agreed upon by the Israelis, the 'Palestinians', and was given official sanction in the aforementioned UN documents (supra).
So in fact, it is legal and moral nonsense, to refer to Israel as 'the occupying power' in any of the above zones, or to assert that Israel must 'halt construction' in Zone C. During the discussions which led to the Interim Agreement of 1995, the PA had requested the addition of a 'side letter' which would restrict construction in Zone C. This request was ultimately withdrawn.
As for the 'settlements' themselves, the usual rationale for 'illegality' is that their existence is a violation of the IV Geneva Convention. This is not the case, because Article II of the aforementioned Convention deals with 'partial or total occupation' of the territory of a High Contracting Party. As Jordan's seizure and subsequent annexation of Judea & Samaria came about following a war of aggression, Jordan does not enjoy this status. (International Law, Malcolm N. Shaw, Fifth Edition, Cambridge University Press 2003, pp. 1061-1063. See also Article XLII, Hague Regulations 1907 and A. Gerson, Israel, the West Bank and International Law). To accord the status of 'High Contracting Party' to Jordan from 1948 onwards would be to legitimize a posteriori armed aggression and land theft. [Obviously, the PLO is not a "high contracting party" either. - EoZ]
The second reason the Convention does not apply can be found in Paragraph 6 of Article XLIX, which states: 'The Occupying Power shall not deport or transfer parts of its own civilian population into the territory it occupies'. To quote Prof. Eugene V. Rostow, former dean of Yale Law School and US Under Secretary of State, 'The Jewish settlers in the West Bank are most emphatically volunteers. They have not been “deported” or “transferred” to the area by the Government of Israel, and their movement involves none of the atrocious purposes or harmful effects on the existing population it is the goal of the Geneva Convention to prevent'.
Also, to cite Professor Julius Stone (former Challis Professor of Jurisprudence and International Law at the University of Sydney and visiting Professor of Law at the University of New South Wales), 'Irony would...be pushed to the absurdity of claiming that Article 49(6), designed to prevent repetition of Nazi-type genocidal policies of rendering Nazi metropolitan territories judenrein, has now come to mean that...the West Bank...must be made judenrein and must be so maintained, if necessary by the use of force by the government of Israel against its own inhabitants. Common sense as well as correct historical and functional context excludes so tyrannical a reading of Article 49(6)'.
I repeat: there is no legal impediment whatsoever to Israeli construction in Zone C, and this is where the currently disputed 'settlements' are located. By demanding that construction be halted, Mahommed Abbas is committing yet another violation of the Oslo Accords (as he did when he went to the UN in September of 2011), and showing that neither he nor his 'Palestinian Authority' can be trusted.
I would add that the PLO leaders regularly say that Israel, by continuing to build in the areas of existing communities, are violating "signed agreements." They seem to be referring to the Roadmap of 2003. But Israel made clear at the time that it did not accept certain parts of the roadmap, and spelled them out.