Israeli airstrikes killed at least six Palestinians guarding aid trucks against looters, Hamas officials said on Friday, as the head of the United Nations warned that only a "teaspoon" of aid was getting in following Israel's 11-week-long blockade, Reuters reported.

The Israeli military said 107 trucks carrying flour and other foodstuffs as well as medical supplies entered the Gaza Strip from the Kerem Shalom crossing point on Thursday, for a total of 305 since Monday when the blockade was relaxed.

But getting the supplies to people sheltering in tents and other makeshift accommodation has been fitful and U.N. officials say at least 500 to 600 trucks of aid are needed every day.

So far, an umbrella network of Palestinian aid groups said, 119 aid trucks have got past the Kerem Shalom crossing point and into Gaza since Israel eased its blockade on Monday in the face of an international outcry, according to Reuters.

Despite the relaxation of the blockade, distribution has been hampered by looting by groups of men, some of them armed, near the city of Khan Younis, an umbrella network representing Palestinian aid groups said.