The head of Palestinian resistance movement Hamas Saturday accused Israel of "war crimes" as the army kept striking Gaza and readied for a possible ground invasion aimed at destroying the group.
"Israeli atrocities amount to war crimes," Ismail Haniyeh charged in a letter addressed to UN Secretary-General Antonio Guterres and posted on the Hamas website.
The heavy bombardment of Gaza has come in retaliation for the Hamas attack on Israel in which its gunmen killed more than 1,300 people, most of them civilians, in the deadliest ever attack on the country.
Israel, stunned by the mass killings and the capture of 150 hostages, has vowed to destroy Hamas and launched strikes that have killed more than 2,200 people in Gaza, also mostly civilians.
It has also cut off water, food and electricity to Gaza and warned it will maintain the siege until the hostages are released.
Haniyeh condemned the "barbaric Israeli siege" in which "the Israeli occupation is banning entry of humanitarian aid and medical supplies to the Gaza Strip".
The Hamas leader -- who has long been based abroad -- urged Guterres to pressure Israel into allowing humanitarian aid to enter into Gaza.
Around 2.4 million Palestinians live in the Gaza Strip, which has been under a crippling Israeli blockade since Hamas seized power in the coastal enclave in 2007.
In a separate statement, Hamas urged humanitarian organisations and Arab and Muslim countries to support Gaza's overwhelmed hospitals and quickly send medical supplies.