This article from Algemeiner, 11 January 2013, is very relevant today, when "Palestinian refugees" are being brutalised by IS in Syria:
Palestinian Authority (PA) President Mahmoud Abbas has said he has rejected a United Nations’ brokered deal with Israel to allow Palestinian refugees living in Syria to resettle in the West Bank and Gaza.
Speaking to a group of journalists in Cairo, Abbas told them that in December  he reached out to UN Secretary-General Ban Ki-moon to contact Israel on his behalf to resolve the status of Palestinians caught in the Syrian civil war.
Abbas, however, said that Israel conditionally agreed as long as the Palestinian refugees forfeit claims to “return” to Israel, which he rejected.
“So we rejected that and said it’s better they die in Syria than give up their right of return,” Abbas reportedly told Egyptian journalists, the Associated Press reported.
...As part of the 1948 War of Independence, more than 700,000 Palestinian Arabs became refugees as a result of the conflict they initiated. Today, the refugees and their descendants (estimated to be around 5 million) remain largely stateless in refugee camps throughout the Arab world.
The UN’s typical policy is that only those who flee their countries themselves are considered “refugees,” not their descendants. However, the UN makes an exception for descendants of Arabs who fled Israel.
In Syria, it is estimated that about 150,000 Palestinians have fled the country as a result of the civil war.
Israel has called for the Palestinian refugee situation to be resolved as part of a comprehensive regional peace deal, while Palestinian leaders have maintained calls for the unconditional return of all refugees to the pre-1948 homes inside of Israel.