There were heavy strikes in and around the main southern city of Khan Yunis, where civil defence agency spokesman Mahmud Bassal said 11 people were killed and several others wounded, along with one more killed in nearby Abasan.

Five people were killed in an air strike near a market west of the northern town of Jabaliya, he said.

In Nuseirat, in the centre of Gaza, three members of the same family were killed in an air strike on their tent, while two people were killed by another strike on a tent in Gaza City, in the north.

Bassal said there were also reports of deaths at the Indonesian hospital in Beit Lahia, but the bodies could not be retrieved due to ongoing shelling.

The ministry of health in Hamas-run Gaza has accused the Israeli army of laying siege to the facility, "effectively forcing the hospital out of service".

The Israeli army said Monday that it was keeping up its newly intensified campaign, adding it was "operating throughout the Gaza Strip".