John Holmes said on Tuesday that to rebuild the war-ravaged Gaza, it is "absolutely critical" that Israel reverse the ban it has enforced since Hamas came to power in 2007 and that it allows cement, pipes and other building materials to enter the Palestinian territory.
He stressed that his top priority will be to get all Gaza border crossings opened as soon as possible "otherwise, the reconstruction effort won't get off first base."
According to press tv, the humanitarian official added that the residents of Gaza are also in a dire need of food and fuel.
Holmes, who is expected to arrive in the occupied territories on Wednesday, told a news conference that he would also press Israeli authorities to allow aid workers from international organizations into Gaza.
According to the UN official, hundreds of millions of dollars in humanitarian aid will be needed immediately to help the nearly 1.5 million Gazans in the strip; billions of dollars will be required to rebuild its shattered buildings and infrastructure.
Israeli Foreign Minister Tzipi Livni said on Tuesday that Israel would not open the border crossings into Gaza without progress on the issue of Israeli soldier Gilad Shalit, who had been captured by Hamas fighters in June 2006.
Hamas has demanded that Israel open the coastal strip's borders. The European Union has also called for the opening of the crossings in order to secure a lasting ceasefire around the territory.
Mussa Abu Marzuq, a senior Hamas official in exile, has commented on the issue of the temporary ceasefire, suggesting that clashes may continue unless Israel ends its 18-month blockade on the strip.
"We in the Palestinian resistance movements announce a ceasefire in the Gaza Strip and demand that enemy forces withdraw in a week and open all the border crossings to permit the entry of humanitarian aid and basic goods," he said on Tuesday.
Israel waged war on Gaza on December 27. At least 1,340 Gazans were killed and at least 5,320 others were injured in the ensuing hostilities.
Holmes said that the UN is trying to intensify humanitarian efforts in Gaza, adding that while some trucks and fuel supplies are getting in, the amount of aid remains small and "very inadequate".
"We need more food, wheat grain in particular both for the humanitarian food distribution and for local bakeries,'' Holmes said.