Turkish President Tayyip Erdogan discussed developments in Syria and Gaza with US counterpart Donald Trump in a telephone call on Tuesday as Syria's Turkey-backed government announced a ceasefire with US-allied Kurdish forces after days of clashes.

Turkey separately weighed if Erdogan should join the US leader's "Board of Peace" initiative.

"President Erdogan stated that Turkey was closely following developments in Syria, that Syria's unity, harmony and territorial integrity were important for Turkey," the Turkish presidency said in a statement.

Earlier Trump said he had a "very good call" with Erdogan, without elaborating.

Syria's government seized swathes of territory in the northeast this week, and gave the Kurdish-led Syrian Democratic Forces four days to agree on integrating into the central state.

The SDF's main ally, the United States, said the partnership with the group had changed nature after Syria's new government emerged.

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The Turkish presidency added that Erdogan and Trump also discussed the fight against the Islamic State militant group and the "situation" of its prisoners in Syrian jails.

Turkey deems the SDF a terrorist organisation linked with the outlawed Kurdistan Workers Party (PKK), which has mounted a four-decade insurgency against the Turkish state.

In its peace process with the PKK, Ankara has called for the group and its affilites to disband and disarm.

Ankara, the main foreign backer of Syria's new government, has praised Damascus' advances against the SDF and repeatedly called for it to integrate with the Syrian state apparatus.

Erdogan thanks Trump for 'board of peace' invite

Erdogan told Trump Turkey would continue to coordinate with Washington on Gaza, the Turkish presidency said.

"President Erdogan thanked US President Trump for the invitation to the Gaza Board of Peace," it added.

A U.N. Security Council resolution, adopted in mid-November, authorized the "Board of Peace" and countries working with it to establish an international stabilisation force in Gaza.

In October, a fragile ceasefire began in Gaza under a Trump plan on which Israel and Palestinian militant group Hamas had signed off.

Earlier on Tuesday, Turkey said Erdogan would decide soon on joining the initiative. Turkey has been critical of Israel's assault on Gaza, casting it as genocide, while Israel has repeatedly opposed a Turkish role in Gaza.

More than 460 Palestinians, more than 100 of them children, and three Israeli soldiers have been reported killed since the Gaza truce began.

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Under Trump's Gaza plan, the board was meant to supervise Gaza's temporary governance. Later Trump said it would be expanded to tackle conflicts around the world.

Many rights experts say that Trump's chairing of a board to supervise a foreign territory's affairs would resemble a colonial structure.

Diplomats fear such a board for global issues could harm the work of the United Nations.

Among those the White House has named to the board are Secretary of State Marco Rubio, Britain's former Prime Minister Tony Blair, and Trump's son-in-law, Jared Kushner.