A medical team of the International Committee of the Red Cross has been permitted into the Gaza Strip, where Israeli forces launched a ground offensive on Saturday.
The Geneva-based ICRC said the specialist team, including a surgeon, had been allowed to enter Gaza at the Erez crossing on Monday.
It will help staff at the Shifa hospital carry out complicated operations on Palestinians that have been wounded in the conflict between Israel and Hamas militants.
The team took with it vaccines against tetanus for children and supplies of blood.
On Sunday, the Swiss-run ICRC said the situation in Gaza had become "both chaotic and extremely dangerous".
It said it was difficult for the ICRC to move around and assess the urgent humanitarian needs created by the continuing shelling and bombing, and by fighting on the ground.
"We are seriously concerned about the reports we are receiving with regard to civilian casualties and damage to civilian objects," commented Pierre Wettach, the ICRC's head of delegation in Israel and the occupied Palestinian territories.
"The safety of civilians is our primary concern in this conflict and we are calling on all parties to spare the lives of all those who are not directly participating in hostilities."
Bern has said that humanitarian access to the Gaza Strip is a priority of Swiss diplomacy. Ambasador Jean-Daniel Ruch told the Swiss News Agency that the civilian population is at present paying a high price in the conflict.
In a related development, the Swiss Red Cross Society launched an appeal on Monday for SFr200,000 ($180.522) for urgent medical supplies for the area.