I encountered that phrase in the following context. The first numbered item in an unofficial translation of the "Casablanca Protocol"of 1965 says: "(1) Whilst retaining their Palestinian nationality, Palestinians currently residing in the land of ___________ have the right of employment on part with its citizens."
Was that supposed to say "on par with"?
Although it is an unofficial translation, it appears at a United Nations website: https://unispal.un.org/UNISPAL.NSF/0/E373EB5C166347AE85256E36006948BA
If United Nations webpages aren't maintained by people who can figure out what is an error to be corrected, and what is correct and should stand unchanged with an explanation added in commentary, then questions like this will continue to arise.
Perhaps I am reading too carefully? Is there a general idea that includes both "on par with" and "on part with"?
Perhaps topics involving Palestinians are thought to be light entertainment to fill up time in television news coverage, and not worth looking at carefully?