Turkey, a close ally of Syria's new authorities which sees Kurdish forces on its border as a security threat, demanded that all Kurdish armed groups -- "including in Syria" -- lay down their weapons.

The implementation of a March deal to merge the Kurds' semi-autonomous administration and military into Syria's new Islamist government has stalled.

Tensions have occasionally erupted into clashes, particularly in Aleppo, which has two Kurdish-majority neighbourhoods.

Both sides traded blame over who started Tuesday's fighting, which continued into the night and is among the deadliest violence between the government and Kurdish forces since the toppling of Bashar al-Assad more than a year ago. It also adds to concerns about progress on the integration deal.

On Tuesday morning, according to the US-backed, Kurdish-led Syrian Democratic Forces, factions affiliated with the government "targeted the Sheikh Maqsud neighbourhood".

By evening, the SDF said the death toll in the Kurdish-majority Sheikh Maqsud and Ashrafiyeh districts had risen to four civilians including two women and a child.

It reported "indiscriminate artillery and missile shelling" on the areas, including "the use of drones... direct sniper fire and heavy-weapon fire".

Sheikh Maqsud and Ashrafiyeh have remained under the control of Kurdish units linked to the SDF, despite Kurdish fighters agreeing to withdraw from the areas in April.

- Stalled integration -

In a statement carried by state news agency SANA, the defence ministry said the SDF targeted "a number of neighbourhoods in Aleppo city adjacent to the districts it controls".

SANA said late Tuesday that SDF fire killed a child in the Al-Midan neighbourhood, after earlier reporting three civilians and a defence ministry member had been killed.

The agriculture ministry said two of those five dead were workers at a research centre.

"The SDF is again proving that it does not recognise the March 10 agreement and is trying to undermine it," the defence ministry said.

Governor Azzam al-Gharib announced schools, universities and government offices in Aleppo city would be closed on Wednesday and public events cancelled.

He cited "the current situation and the targeting of several hospitals and institutions by indiscriminate SDF artillery shelling".

The SDF controls swathes of Syria's oil-rich north and northeast, and supported by a US-led international coalition was key to the territorial defeat of the Islamic State group in Syria in 2019.

The March agreement on its integration into the state was supposed to be implemented by the end of 2025.

- 'Lay down' weapons -

In Ankara, Turkish Defence Minister Yasar Guler said "the PKK (the Kurdistan Workers' Party) and all affiliated groups must immediately cease all terrorist activity in regions where they are present, including in Syria, and lay down their weapons without condition".

The SDF is dominated by the People's Protection Units (YPG), a Kurdish militant group seen by Ankara as an extension of the PKK, which earlier this year agreed to end its four-decade armed struggle against Turkey.

"We will not allow any terrorist organisation -- particularly the PKK, the PYD, the YPG, and the SDF -- to establish a foothold in the region," Guler added.

Turkey, which shares a 900-kilometre (550-mile) border with Syria, has launched successive offensives to push Kurdish forces from its frontier.

Also Tuesday, the SDF accused factions affiliated with Syria's army of attacking Deir Hafer, around 50 kilometres (30 miles) east of Aleppo, and near the strategic Tishreen Dam to the city's northeast.

The Kurdish-led force affirmed its right to "respond legitimately to these attacks".

On Sunday, SDF chief Mazloum Abdi held further talks with officials in Damascus on integrating the Kurdish-led forces, but state media reported no tangible results.

The Kurds have insisted on decentralisation, which Syria's new Islamist authorities have rejected.

Last month in Aleppo, clashes killed five people, while Turkish Foreign Minister Hakan Fidan urged the SDF not to be an obstacle to Syria's stability.