Here are the latest developments in Syria:

• Ceasefire talks held between Kurdish-led Syrian Democratic Forces and Syrian leadership on Monday didn't go well, sources say
• Despite the announcement of an immediate ceasefire on Sunday, clashes between the SDF and Syrian government forces were reported on Monday
• Some 1,500 IS members escaped from Shaddadeh prison, the SDF say

Syria's Sharaa discusses fragile ceasefire with Kurdish leader Abdi

It's currently unclear exactly how the ceasefire talks between interim President Ahmad al-Sharaa and Mazloum Abdi, the commander of the Kurdish-led Syrian Democratic Forces (SDF), on Monday.

Abdi issued no statement after the meeting in the capital Damascus, according to the Associated Press.

But a Kurdish source with knowledge of the talks told the AFP news agency they weren't positive.

Reuters also reported reporting that the meeting "didn't go well."

It cited a Kurdish source as saying that Abdi is dissatisfied with the ceasefire terms and requested more time to discuss the matter with his fellow commanders.

Abdi also repeated his proposal for the SDF to integrate into Syria's army as units rather than individuals, the source said.

The meeting came after the two sides agreed to an immediate ceasefire on Sunday.

What was the fighting reported on Monday?

An AFP correspondent reported hearing heavy bombardment in Raqqa in northern Syria on Monday evening.

A defence ministry source later told AFP that the clashes had halted, without elaborating.

In a Facebook post, the SDF said "violent clashes" took place between its forces and government forces in the vicinity of Raqqa's Al-Aqtan prison. This "houses detainees of the ISIS terrorist organization, representing an extremely dangerous development," it said.

An Associated Press journalist reported seeing a US convoy entering the prison area.

The Syrian government seized much of the northern province of Raqqa, along with the eastern oil-rich province of Deir el-Zour, from the SDF on Sunday as part of its push against the Kurdish forces.

Raqqa was once the de facto capital of so-called "Islamic State" group in Syria, but the SDF, backed by an international coalition, later expelled the Islamic group from the city during Syria's civil war.

What do we know about IS fighters escaping prison?

On Monday, IS fighters escaped from a prison in the town of Shaddadeh, around 50 kilometers (31 miles) from Syria's border to Iraq.

Both government forces and the SDF traded blame for the escapes. The army accused the SDF, who controlled the prison, of releasing the detainees.

The Kurdish-led SDF said they lost control of the prison after an attack by government forces.

The Syrian ‍army denied attacking the jail and said its forces would work to secure the prison and re-arrest the escapees. It didn't say how many prisoners had escaped.

Kurdish news outlet Rudaw put the numer of escapees at around 1,500, citing an SDF spokesperson.

Government forces imposed a curfew in Shaddadeh because of the breakout.

The SDF controls more than a dozen prisons in the northeast where an estimated 9,000 of IS members have been held for years.

Many of the detained extremists are believed to have carried out atrocities in Syria and Iraq after IS declared a caliphate in June 2014 over large parts of the two countries.

Calls for peace in Syria

In a call on Monday, US President Donald Trump apparently urged Sharaa to halt violence between government forces and the SDF.

That's according to a readout of the call issued by Syria's presidency.

The Syrian presidency said both sides stressed the need to guarantee the rights and protection of the Kurdish people within the framework of the Syrian state.

The statement said Trump and Sharaa also agreed to continue cooperating in the fight against IS.

EU foreign policy chief Kaja Kallas said "all military activities must cease immediately."

Turkish President Recep Tayyip Erdogan hailed Syria's army for its "careful" offensive despite what he called "provocations."

While the SDF has been the United State's main partner in Syria in the fight against IS, Turkey considers it to be a terrorist group because of its ties to the Kurdistan Workers' Party, or PKK, a Kurdish separatist group that has mounted a long-running insurgency in Turkey.

Edited by: Zac Crellin