The United Nations has criticised the resumption of conflict in Gaza on Friday, describing the attacks as "catastrophic" and urging parties to bring about a lasting ceasefire.

Jens Laerke, spokesperson for the UN humanitarian office in Geneva, said that with the resumption of Israel's hostilities towards Palestinians, "hell on Earth has returned to Gaza".

Israeli resumed bombing Gaza after a 7-day truce ended with no deal to extend it. Dozens of Palestinians have died with the millions of already displaced desperately seeking shelter.

"The resumption of hostilities in Gaza is catastrophic," said Volker Turk, the UN High Commissioner for Human Rights. He urged all parties and stated with influence to double the efforts to ensure an immediate ceasefire, citing humanitarian and human rights grounds.

UN Secretary-General Antonio Guterres said he regretted the resumption of hostilities and hoped a new pause could be established, in his post on X.

"The return to hostilities only shows how important it is to have a true humanitarian ceasefire," he said.

Over 15,000 Palestinians have been killed since 7 October.