The aid agency says its buildings in the central part of the territory were attacked after the military targeted Deir al-Balah, which had largely been spared.

The expansion of Israel’s ground invasion comes as Israel and Hamas have been considering terms for a ceasefire for Gaza that would pause the fighting and free at least some hostages.

Israel's military on Tuesday responded to accusations by the World Health Organization (WHO) that its forces attacked the UN agency's facilities in central Gaza and detained staff members. The military said soldiers came under fire in the city of Deir al-Balah on Monday and returned fire in the direction the shots originated.

Israel Defense Forces pushed into a central Gaza city on Monday for the first time since the war with Hamas began.

The area is packed with Palestinians who left their homes during 21 months of war in Gaza, hundreds of whom fled west or south after Israel issued an evacuation order on Sunday. Israeli tanks pushed into the southern and eastern districts of the Gazan city of Deir al-Balah on Monday,

The Israeli military has, for the first time in the ongoing Gaza war, moved ground troops into parts of Deir al-Balah, eyewitnesses said on Monday. Israeli soldiers are reported by city residents to have taken control of buildings in the south-west of the city in the central Gaza Strip and positioned snipers on the rooftops.