The top United Nations humanitarian official arrived in Jerusalem on Wednesday to begin an assessment of the needs on the ground in the Gaza Strip following the three-week Israeli military offensive that came to a halt just a few days ago, UN officials announced here. UN Under-Secretary-General for Humanitarian Affairs John Holmes will lead a humanitarian needs assessment team into Gaza on Thursday, together with the UN special coordinator for the Middle East peace process, Robert Serry, the officials said. [...] The World Food Program (WFP) is trying to help by delivering flour to bakeries, and WFP-contracted bakeries are now working to produce 5,000 three-kilogram bread parcels per day. WFP also reports that a first shipment of 10 tons of nutritious date bars --supplied by Egypt under WFP's Operation Lifeline Gaza -- made it into Gaza Tuesday. At the same time, the UN agency remains concerned by security constraints, which are limiting access to its warehouses. It does not have access currently to some 520 tons of food, or 12 percent of WFP's current stocks in Gaza.