U.N. Secretary-General Ban Ki-moon, just back from a visit to the Gaza Strip, says he was "deeply affected" by the destruction and suffering he witnessed. He called on Israel and Hamas to turn their unilateral cease-fires into a lasting peace.

The U.N. chief made a week-long trip to the Middle East, visiting seven countries and the occupied Palestinian territories in a bid to end the fighting in Gaza. His talks with leaders at every stop left him with laryngitis by the time he returned to brief the Security Council Wednesday afternoon.

Stepping in, Under-Secretary-General for Political Affairs, Lynn Pascoe, who accompanied Mr. Ban on the trip, read the U.N. chief's remarks to the 15-member council.

"The fighting has ended with declarations of unilateral cease-fires, and, today [Wednesday], the withdrawal of Israeli troops," he said. "This is an important achievement and offers a much-needed respite for suffering civilians, especially in the Gaza Strip. But conditions are still fragile and much more remains to be done on both the humanitarian and diplomatic fronts."

The secretary-general said he is counting on regional and international leaders to continue these efforts to find areas of agreement and ways to ensure that a durable and lasting cease-fire is quickly implemented - one that includes lasting arrangements to prevent the smuggling of arms and ammunition to Hamas and ensures the sustained reopening of Gaza border crossings.

Mr. Ban visited Gaza on Tuesday. He said he wanted to show his respect and concern for the injured and dead.

"I wanted to send a signal that the United Nations stands with the people who have borne tragedy and disaster, and that we will not abandon them," continued Pascoe, reading the secretary-general's remarks.

Mr. Ban also met residents in the southern Israeli city of Sderot - long a target of Hamas rocket fire and where three Israelis have been killed during the conflict.

Mr. Ban said that in both places, he underscored the need for international humanitarian law to be fully respected and for civilians to be protected. He said that where civilians have been killed or there are allegations of violations of international humanitarian law, there should be investigations, full explanations, and where it is required, accountability.

Fifty U.N. facilities have been damaged in the hostilities. Among them, three U.N.-run schools that were hit by Israeli fire. In one incident, more than 40 civilians were killed. In another, a U.N. warehouse full of food and medicine burned to the ground. And in another incident, two young brothers were killed.

Under-Secretary-General Lynn Pascoe said Mr. Ban visited some of these sites and expressed his outrage.

"When I met Israeli leadership on several occasions, I demanded a thorough investigation into every single one of these incidents," Pascoe read from Ban's written remarks. "I expect to receive a full explanation of each incident and those responsible will be held accountable for their actions."

Mr. Ban said once the Israelis report their findings to him, he will decide on the appropriate follow-up action.

The secretary-general also stressed that humanitarian relief is the number one priority in Gaza. He has dispatched a high-level U.N. team there to assess the immediate needs, and an appeal for hundreds-of-millions of dollars in aid is expected in about 10 days.

Following the secretary-general's briefing, the Security Council issued a statement welcoming the cease-fire and the efforts of the U.N. chief as well as those of regional and international players, especially Egypt, in bringing it about.