ISTANBUL : Nearly half of the schools run by the UN's agency for Palestinian refugees have been hit by conflict in the last five years, it said on Monday on the sidelines of the World Humanitarian Summit in Istanbul.

UN Secretary General Ban Ki-moon earlier reminded participants on the opening day of the two-day summit that attacks on schools and hospitals in conflict cannot go unpunished any longer.

But the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) said 302 out of 692 schools it runs for Palestinian refugees in Syria, Lebanon, the Gaza Strip and West Bank have suffered damage due to conflict in the last half decade.

"Nearly half of the 692 schools run across the region have been impacted, attacked or otherwise rendered inoperable by conflict or violence in the last five years," it said in a report unveiled at the summit.

UNRWA's Commissioner-General, Pierre Kraehenbuehl, complained that the figure was "staggering".

Kraehenbuehl called on states and non-state parties to "refrain from such attacks, to respect the civilian character of UN installations and to spare the lives of children, civilians and humanitarian workers."

He said that protecting schools against the effects of conflict was a "key test" of the world's ability to deliver on its humanitarian commitments.

The UNRWA report said that in Syria five years of war have rendered over 70 per cent of its schools inoperative, due to damage, access restrictions or the need for schools to be used as shelters.

Before the outbreak of the conflict, UNRWA operated 118 schools throughout Syria but 34 have been fully or partially damaged and currently only 44 are open, it said.

Even after half a decade of war, an estimated 450,000 Palestinian refugees remain in Syria, it said.

UNRWA complained the Israeli blockade on the Gaza Strip had a "devastating effect" on refugee children, while clashes in Lebanon had also damaged schools.

UNRWA, established in 1949, provides protection to some five million registered Palestinian refugees.

It said it was seeking to counter the problems by providing self-learning materials and facilities, rebuilding damaged schools and and seeking accountability for attacks against UNRWA schools