Stephen, UN resolution 181 does not describe the internationally accepted borders of Palestine because the Palestinians violently rejected the plan and invaded the newborn Israel in what turned out as a failed landgrab attempt. By no international standards does this kind of action get rewarded. The closest we have to an internationally recognised border is the cease-fire line of 1949, the Green Line, and Ashqelon is very much on Israel's side of it.
Key U.S. House Democrat cites troublesome issues in Iran nuclear deal (Reuters)
from the article: Palestinian activists urge Hamas to probe own Gaza war crimes