UNITED NATIONS, July 25 -- UN Secretary-General Ban Ki- moon has been in intense discussions with a number of key interlocutors, including Egyptian Foreign Minister Sameh Shukry and U.S. Secretary of State John Kerry, to build support for a possible ceasefire in Israel and Gaza, a UN spokesman said here Friday.

On the secretary-general's diplomatic efforts in the region, Farhan Haq, the deputy UN spokesman, said at a daily news briefing that Ban had also spoken by phone with the foreign ministers of Turkey and Qatar to see what kind of pressure could be brought on all side to obtain a ceasefire between Israel and Hamas, a radical militant group in Gaza.

The UN chief Friday also spoke to the staff of the UN Relief and Works Agency (UNRWA) in Gaza by video link to express his deep appreciation and thanks for the brave work that they were doing, Haq said.

The secretary-general has repeatedly called for an immediate halt to the fighting between Israel and Hamas militants in Gaza, urging the parties to look at root causes of the violence so that the fighting that Gaza has experienced in recent years does not recur, Haq added.

On Thursday, a strike on a United Nations school in Beit Hanoun in northern Gaza killed at least 15 Palestinians and injured 200 others, mostly women and children.

Ban arrived in Cairo on Thursday after visiting Iraq.