Israel's military says it has launched attacks on Hamas targets in a refugee camp in central Gaza, raising fears of more civilian casualties in new ground offensives.

Spokesperson Daniel Hagari said on Tuesday that the military expanded the fighting to an area known as the central camps.

The military said it attacked the targets in the Bureij refugee camp after urging residents there and in other central Gaza areas to evacuate.

Footage released by the Reuters news agency showed residents carrying baggage and walking down streets, with one of them saying they had been forced out.

After taking effective control in northern Gaza, Israeli forces have been intensifying their offensive in Khan Younis in the south, where they say Hamas leaders are hiding.

On Sunday, an Israeli air strike hit another refugee camp in central Gaza. Health authorities in the enclave said 68 people have died.

The announced expansion of Israel's ground offensive to the area has raised fears of more civilian casualties.

A UN special rapporteur on the human rights of internally displaced persons said in a statement issued on Friday that "evacuation orders and military operations continue to expand and civilians are subjected to relentless attacks on a daily basis."

The special rapporteur added, "the only logical conclusion is that Israel's military operation in Gaza aims to deport the majority of the civilian population en masse."