There are between 13-15 million Palestinians in the world, the Department of Refugees Affairs in the Hamas government said.
In a statement, the body said it used data from the Palestinian Central Bureau of Statistics, UNRWA, the websites of Palestinian communities in different countries as well as Palestinian research centres to gather the information.
The department noted that it is not easy to estimate the exact number of Palestinians because they constantly move between countries.
The head of the department, Issam Adwan, said six million Palestinian refugees are registered with UNRWA, but there are many unregistered refugees.
"There are refugees who were displaced between major wars (1948-1967), there are the deportees, some Palestinians have lost their ID cards as well as those who left Palestine before 1948 and were unable to return because of the war. Therefore, it is natural that the number of Palestinian refugees could reach 10.5 million, representing about 70 per cent of the Palestinian population," he explained.