Considered a pragmatist, Haniyeh has been head of Hamas' political bureau since 2017, though he lives in exile, splitting his time between Turkey and Qatar.

He was recently involved in talks aimed at bolstering the Cairo-brokered ceasefire that ended the latest deadly violence between the Jewish state and Hamas. The 11-day conflict in May killed 13 Israelis and 260 Palestinians, including some fighters.

Hamas won the last legislative elections in Gaza, an impoverished Palestinian enclave of nearly two million, in 2006, delivering a surprise defeat to rivals Fatah.

A virtual civil war the following year led to the division of Palestine, with Fatah dominating the Palestinian Authority in the West Bank and Hamas ruling the Gaza Strip.

Israel has blockaded Gaza since then, citing repeated attacks, while Hamas has been internationally shunned and declared a terrorist group by the European Union and the United States.

Haniyeh's victory finalises a poll process that began last March with the re-election of Hamas' local Gaza chief Yahya Shinwar. Further voting was postponed due to May's clashes with Israel.

Read more from Middle East