The World Food Programme (WFP) had planned to send four convoys from Beirut, three to the south and one to the north, but had to postpone two of them because neither Israel nor Hezbollah gave the needed assurances, the UN agency's spokeswoman in Geneva, Christine Berthiaume, said on Tuesday.
Four ICRC convoys of trucks were unable to leave Tyre in south Lebanon with food, water and medicine for the same reason, spokeswoman Annick Bouvier said.
"We did not receive the green light," Bouvier said.
Before setting off, the agencies give notice to the Israelis and Hezbollah of where they plan to go and when. Only if the two sides acknowledge the plans will they set out.
In Brussels, European Benita Ferrero-Waldner, the external relations commissioner, said: "The 48-hour agreement on humanitarian aid which was called has not worked and has not been adhered to by either side. This is very disappointing and shows the depth of the problem.
"The first priority must be to get the 48-hour truce working properly to get aid in and then get a ceasefire."
Air strikes suspended
Israel announced early on Monday a partial suspension of air strikes for 48 hours and a 24-hour window for aid workers to reach the worst hit areas of for residents of south Lebanon to flee.
Bombed roads and bridges have hindered access to the area.
Israeli troops made new thrusts into southern Lebanon on Tuesday and pounded towns and villages, meeting fierce resistance from Hezbollah fighters.
A senior Israeli cabinet member said the army needed up to two more weeks to finish its offensive.
Aid agencies finally began moving relief supplies into south Lebanon last Wednesday after Israel agreed to open a "humanitarian corridor".
But medical charity Medecins Sans Frontieres (MSF) or Doctors Without Borders said on Friday that there was "no real humanitarian access in the south".
The ICRC convoys were made up of three or four trucks, each carrying enough food for a family of five for a week, together with hygiene items and fuel for water pumps, Bouvier said.
They were to be accompanied by Lebanese Red Crescent Society ambulances to help evacuate civilian victims of the fighting.
The Finnish EU presidency said humanitarian aid pledged by the EU and individual member states now totalled €108 million ($138 million).
A spokesman said that in addition, significant contributions in kind had been made.