"It's a kind of humanitarian alibi because in effect there is no real humanitarian access in the south," said Christopher Stokes of Medecins Sans Frontieres (MSF) or Doctors Without Borders.
"The international community is deluding itself, if it believes there is."
Aid convoy hit
On Friday, suspected Israeli shells fell near an aid convoy in south Lebanon, wounding at least three people, witnesses told Aljazeera.
They said the convoy, organised by Lebanese civil defence workers, was returning from the village of Rmeish to the port city of Tyre after evacuating dozens of civilians.
One vehicle was damaged and three civilians were wounded. Some foreign and local journalists were in the convoy.
MSF praised the courage of Lebanese relief workers and medical staff, saying they were the ones doing most of the humanitarian work in the area.
"We have had contacts [with the Israeli army]. They have not been very productive, in terms of having contacts for security guarantees and we not been given any encouragement that we would have the guarantees to work in the south," Stokes said.
Stokes made his remarks as the International Committee for the Red Cross, announced it was increasing its appeal for aid to Lebanese affected by the fighting to $81 million.
Unable to move supplies
Robin Lodge, of the World Food Programme (WFP) said the organisation had been unable to move supplies trucked to Tyre beyond to villages in the south.
Lebanese civilians continue to be|
injured by Israeli air raids
He said the best they could do at the moment was inform the warring parties of where and when they wanted to deliver aid.
The UN estimates there are up to 800,000 people in Lebanon displaced by the fighting and bombing.
"But for security reasons we are not able to get the areas south of Tyre," he said. "We are keenly aware of the needs."
It said there are nearly 600 schools being used as shelters, with between 100 and 1,200 people in each school.
The Lebanese authorities say up to 600 civilians have been killed during the 17-day Israeli onslaught.
UN withdraws observers
Meanwhile, the UN said its peacekeeping mission in south Lebanon had withdrawn eight unarmed observers from two observations posts along the border with Israel.
The move brought to four the number of unoccupied UN bases in the area, out of a total of more than 40 outposts.
UN observers had been pulled out of a base at Marun al-Ras five days earlier after an Italian peacekeeper was seriously wounded by Hezbollah small arms fire.
A second base was left unmanned after it was destroyed by an Israeli air strike on Tuesday that killed all four observers on duty there.
The four were part of the UN Truce Supervision Organisation, a unit of about 155 observers under the command of the UN Interim Force in Lebanon, known as UNIFIL, which has about 1,990 troops in the area.