Israel's foreign minister said Saturday the United Nations had become an "anti-Israeli body" under Antonio Guterres, after the UN chief called for a ceasefire on a visit to Gaza's border.

International outrage over the heavy civilian toll and humanitarian crisis in Gaza, where Israel battles Hamas militants, has further worsened the long strained ties between Israel and the world body.

"Under his (Guterres's) leadership, the UN has become an anti-Semitic and anti-Israeli body that shelters and emboldens terror," Foreign Minister Israel Katz said on social media platform X.

The top Israeli diplomat criticised Guterres, who Katz said "stood today on the Egyptian side of the Rafah crossing and blamed Israel for the humanitarian situation in Gaza", claiming instead that Hamas militants "plunder" aid.

Katz, whose government has accused staff at the UN agency for Palestinian refugees of involvement in Hamas's October 7 attack that triggered the war, also said Guterres spoke "without calling for the immediate, unconditional release of all Israeli hostages".

But in Rafah, the UN chief said: "In the Ramadan spirit of compassion, it is also time for the immediate release of all hostages" still held by militants in Gaza.