The 16, who will spend three days in the Islamist-ruled territory, arrived in the Gaza Strip through its Rafah crossing with Egypt, a Hamas official told AFP.
They are charged with evaluating judicial procedures that may be taken by Israel and the Palestinians following the Goldstone report into the 22-day war between December 2008 and January last year that killed some 1,400 Palestinians and 13 Israelis.
South African judge Richard Goldstone's lengthy UN-mandated report accused both Israel and Palestinian groups of committing war crimes during the conflict.
The 575-page report by a panel led by Goldstone recommended that its findings be transferred to the International Criminal Court in The Hague if Israel and Hamas fail to conduct credible investigations into the war.
From the outset, Israel rejected the Goldstone report as biased and refused to cooperate with the UN inquiry panel.
In February, UN Secretary General Ban Ki-moon told the General Assembly he had been unable to determine whether either Israel or the Palestinians had begun credible inquiries into the Goldstone report's allegations.