Trump sparked uproar earlier this year by declaring that America would take over Gaza and turn it into the "Riviera of the Middle East", prompting Arab leaders to come up with a plan to rebuild the territory at a March summit in Cairo.

Palestinian president Mahmud Abbas was the first Arab leader to arrive in Baghdad Friday.

Egyptian President Abdel Fattah al-Sisi and Qatari emir Sheikh Tamim bin Hamad Al Thani arrived on Saturday morning.

But a diplomatic source said most Gulf states would be represented by ministers.

The war in Gaza is expected to dominate the agenda, especially after Israel approved plans to expand its offensive and spoke of the "conquest" of the territory.

The Israeli military said it had launched "extensive strikes" on Saturday as part of the "initial stages" of a fresh offensive in Gaza.

United Nations chief Antonio Guterres will attend the summit, and Spanish Prime Minister Pedro Sanchez -- who has sharply criticised the Israeli offensive -- is expected to address it as a guest.

Iraqi Foreign Minister Fuad Hussein said the Baghdad meeting would endorse decisions that were made at the March summit in Cairo to support Gaza's reconstruction as an alternative to Trump's widely condemned proposal.

The president reiterated the proposal on his Gulf tour this week, saying in Qatar on Thursday that he wanted the United States to "take" Gaza and turn it into a "freedom zone".

- Syria, Iran -

Iraq has only recently regained a semblance of normality after decades of devastating conflict and turmoil, and its leaders view the summit as an opportunity to project an image of stability.

In an opinion piece about the summit earlier this month, Prime Minister Mohammed Shia al-Sudani wrote: "Today, we are not just rebuilding Iraq, we are also reshaping the Middle East through a balanced foreign policy, a wise leadership, development initiatives and strategic partnerships."

Baghdad last hosted an Arab League summit in 2012, during the early stages of the civil war in neighbouring Syria, which in December entered a new chapter with the overthrow of longtime ruler Bashar al-Assad.

In Riyadh, Trump met Syria's interim President Ahmed al-Sharaa, a onetime jihadist whose Islamist group spearheaded the offensive that toppled Assad.

Sharaa, who was imprisoned in Iraq for years after the US-led invasion of 2003 on charges of belonging to Al-Qaeda, will miss the Baghdad summit after several powerful Iraqi politicians voiced opposition to his visit.

Foreign Minister Asaad al-Shaibani will represent Damascus instead.

The summit also comes amid Iran's ongoing nuclear talks with the United States.

Trump has pursued diplomacy with Iran as he seeks to avert threatened military action by Israel -- a desire shared by many of the region's leaders.

On Thursday, Trump said a deal was "getting close", but by Friday, he was warning that "something bad is going to happen" if the Iranians do not move fast.