The European Union's foreign policy chief, Josep Borrell, has criticised the United States for giving its ally Israel a month to "improve the humanitarian situation" in the Gaza Strip, warning that "a very large number" of Palestinians could be killed during that period.

"The United States is telling Israel that it must improve humanitarian support to Gaza, but they have given it a one-month deadline, one month at the current rate of people being killed... (meaning) a very large number (of dead), the situation is catastrophic," Borrell told reporters on Thursday ahead of a summit of EU leaders in Brussels.

US officials said Tuesday that Israel must take steps within a month to improve the humanitarian situation in Gaza or face possible restrictions on US military aid.

Washington's giving its ally Tel Aviv a month, according to observers, is an "inhumane act" in light of the catastrophic current situation in Gaza, and aims to give Israel time to implement what it calls the "generals' plan" in the northern Gaza Strip.