Israel launched an intensive ground offensive into Gaza City on Tuesday as it gained "unwavering support" from the United States to crush Hamas, defying calls from an emergency Arab-Islamic summit in Doha on Monday, which strongly condemned recent Israeli attacks on Qatar-hosted Hamas officials heading for Gaza ceasefire talks.

"Gaza is burning," Israeli Defense Minister Israel Katz said on Tuesday, adding the military was striking "with an iron fist at the terrorist infrastructure".

"We have launched a significant operation in Gaza," Israeli Prime Minister Benjamin Netanyahu confirmed later at a court in Tel Aviv.

Local media reported Israeli tanks had entered Gaza City following massive airstrikes, and residents said Israeli bombardment had increased dramatically over the past two days. Naval vessels have joined in the operation, leaving more civilians dead and injured.

On Tuesday, the United Nations Independent International Commission of Inquiry on the Occupied Palestinian Territory, including East Jerusalem, and Israel concluded that Israel has committed genocide against Palestinians in the Gaza Strip, citing a pattern of genocidal conduct by Israeli officials and civilians.

In its report, the commission urged Israel and all states to fulfill their legal obligations under international law "to end the genocide and punish those responsible for it".

"The Commission finds that Israel is responsible for the commission of genocide in Gaza," said Navi Pillay, chair of the commission.

She added it "is clear that there is an intent to destroy the Palestinians in Gaza through acts that meet the criteria set forth in the Genocide Convention", including killing, causing serious bodily or mental harm, and deliberately inflicting conditions of life calculated to bring about the destruction of the Palestinians.

In a post on X, Israel's Foreign Ministry rejected the report and called for the immediate abolition of this commission of inquiry.

Ahmad Ghouri, an associate professor at the School of Law, Politics and Sociology at the University of Sussex in Britain, told China Daily that the report is "a significant legal and moral finding, and it places pressure on governments and institutions worldwide to respond".

The new Israeli aggression came one day after the Arab League and the Organization of Islamic Cooperation held a joint emergency summit in Doha, which brought together nearly 60 countries and sought to take firm action after Israel's attack last week.

Reviewing relations

The final communique urged "all states to take all possible legal and effective measures to prevent Israel from continuing its actions against the Palestinian people", including "reviewing diplomatic and economic relations with it, and initiating legal proceedings against it".

It also urged member states to "coordinate efforts aimed at suspending Israel's membership in the United Nations".

The leaders reiterated support for Palestinian statehood based on 1967 borders with East Jerusalem as its capital, welcomed an upcoming UN conference on the implementation of the two-state solution in New York, and praised Qatar's role in mediation, humanitarian aid and fostering Arab and Islamic unity.

The host country's emir, Sheikh Tamim bin Hamad Al Thani, said the summit sends a clear message in the face of Israel's "state terrorism".

"Whoever works diligently and systematically to assassinate the party with whom he is negotiating, intends to thwart the negotiations," the emir said, adding that Netanyahu is dreaming of making the Arab region "an Israeli sphere of influence".

Talking of Israeli strikes against Doha, Iranian President Masoud Pezeshkian said, "Tomorrow, it could be the turn of any Arab or Islamic capital." Iran fought back Israeli and US aggression for 12 days in June before securing a ceasefire.

The Gulf Cooperation Council, which includes Qatar, Saudi Arabia and the United Arab Emirates, also met on the sidelines of the summit, urging the US to use its "leverage and influence" to rein in Israel, GCC Secretary-General Jasem Mohamed Al-Budaiwi said.

Consultations were underway among the bloc's military bodies to build up "Gulf deterrent capabilities", with a meeting of the group's Unified Military Command set to take place soon in Doha, said Majed Mohammed Al-Ansari, Qatar's Foreign Ministry spokesman.

The Israeli attack on Doha strained ties between Washington and key allies in the Gulf, raising concerns over US security guarantees in a region housing major US assets, including a major military base in Qatar.

However, during a joint news conference with Netanyahu in Jerusalem on Monday, US Secretary of State Marco Rubio backed Israel's new offensive on Gaza City and the goal of eradicating Hamas.

"You can count on our unwavering support," he told Netanyahu.

On his way to Doha from Tel Aviv on Tuesday, Rubio said the US and Qatar are on the verge of finalizing an enhanced defense cooperation agreement, without elaborating.

He also called on Qatar to continue its role as a mediator between Israel and Hamas to reach a ceasefire, saying there was "a very short window of time in which a deal could happen".

Jan Yumul in Hong Kong and agencies contributed to this story.