From CNN’s Caitlin Danaher in London

The United Nations has “unequivocally condemned” attacks on civilians in Israel and Gaza, and also Israel’s “further tightening of the unlawful blockade,” in a statement released Thursday.

The killings and hostage-taking by Hamas “constitute heinous violations of international law and international crimes, for which there must be urgent accountability,” the statement read.

There is no justification for such violence in Israel or Gaza, the statement said.

The UN also focused on the plight of Palestinians in Gaza.

“We also strongly condemn Israel’s indiscriminate military attacks against the already exhausted Palestinian people of Gaza, comprising over 2.3 million people, nearly half of whom are children. They have lived under unlawful blockade for 16 years, and already gone through five major brutal wars, which remain unaccounted for,” they said. “This amounts to collective punishment.”

The experts also warned the withholding of essential supplies, such as food, water and medicine, will “precipitate a severe humanitarian crisis in Gaza, where its population is now at inescapable risk of starvation.” They called for the establishment of humanitarian corridors to allow people to leave Gaza.

The UN urged the international community to “address the root causes of the current conflict, including the 56-year-old occupation and the annexation pursued by Israel.”