Israel says the seizure of territory in Gaza is aimed at pressuring Hamas to release hostages, but it is a major point of contention in ongoing cease-fire talks.

Israeli tanks on Monday rolled into a part of central Gaza that has not previously seen ground operations in the 21-month war, according to Israeli media, aid agencies and witnesses.

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 foreign ministers of 25 Western nations have slammed Israel for “drip feeding” aid into the Gaza Strip, as the health ministry in the territory said that more than 1,000 people have been killed seeking humanitarian relief there since late May.

The World Food Program in a statement Sunday condemned the violence that erupted in northern Gaza as Palestinians tried to reach a convoy of trucks carrying food. The Health Ministry in Gaza said at least 80 people were killed in the incident.