Israel on Saturday hit parts of Gaza including Rafah where it expanded an evacuation order, as the UN warned an outright invasion of the crowded city risked an "epic" disaster, reports BSS.

AFP journalists, medics and witnesses reported strikes across the coastal territory, where the UN says humanitarian relief is blocked after Israeli troops defied international opposition and entered eastern Rafah this week.

At least 21 people were killed during strikes in central Gaza and taken to Al-Aqsa Martyrs Hospital in Deir al-Balah city, a hospital statement said.

Bodies covered in white dust lay on the ground in a courtyard of the facility. A man in a baseball cap leaned over one body bag, clasping a dust- covered hand that protruded.

The feet of another corpse poked from under a blanket bearing the picture of a large teddy bear.

In Rafah, witnesses reported intense air strikes near the crossing with Egypt, and AFP images showed smoke rising over the city.

Other strikes occurred in north Gaza, witnesses said.

Hamas on Saturday accused Israel of "expanding the incursion into Rafah to include new areas in the centre and the west of the city".

Israeli troops on Tuesday seized and closed the Palestinian side of the Rafah crossing -- through which all fuel passes into Gaza -- after ordering residents of eastern Rafah to evacuate.

The army said Saturday troops were fighting "armed terrorists" at the crossing and had found "numerous underground tunnel shafts".

Bd-pratidin English/Tanvir Raihan