The Palestinian Central Bureau of Statistics said today it has recorded a population of 12.1 million people, of whom 4.6 million live in the occupied territories and the remainder abroad.
The figures show that at the end of 2014, 2.8 million Palestinians lived in the West Bank and 1.8 million in the Gaza Strip.
In the impoverished Gaza enclave, the population of 4.9 people per square kilometre makes its density one of the world's highest.
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The balance of 7.5 million Palestinians live in exile, the majority in 31 UN-installed refugee camps in Jordan, Lebanon and Syria.
UNRWA, the world body's aid agency for Palestinian refugees, has 5.49 million people registered on its books.
The figures were announced ahead of Friday's 67th anniversary of the "Nakba", or "catastrophe" in Arabic, the day when Palestinians mourn Israel's establishment in 1948.
In a statement, the head of the statistics bureau said that in 1948, "1.4 million Palestinians lived in 1,300 towns and localities in historic Palestine".
After the war that followed Israel's creation, "Israel took control of 774 towns and villages, destroyed 531 and committed 70 killings and massacres in which 15,000 people died", she said.
Some 154,000 Palestinians decided to remain on their land after that conflict, and their Arab Israeli descendants now number nearly a million and a half.