At least 23 fighters were killed in the fighting between the Kurdish-led alliance and the Islamist rebels who include Al-Qaeda's Syrian affiliate, Al-Nusra Front, said the Syrian Observatory for Human Rights.

Fifteen fighters from Al-Nusra and its allies were killed Sunday, along with at least eight members of the Syrian Democratic Forces dominated by the Kurdish People's Protection Units (YPG).

The clashes in the northern province of Aleppo began Thursday, when the Islamists attacked posts belonging to Jaish al-Thuwwar, an Arab rebel group allied with Kurds, said Kurdish journalist Arin Shekhmos.

The assault, near the Turkish border region of Azaz, prompted sporadic fighting that drew in the SDF and also saw Al-Nusra and its allies fire rockets at a Kurdish district of Aleppo city.

Syria's Kurds have long had tense relations with parts of the armed opposition, particularly its hardline elements.

The minority never joined the armed uprising against President Bashar al-Assad, despite having been oppressed by his regime.

It has refused to allow rebels to stage operations from Kurdish-majority regions, from which the regime withdrew in 2012, and has focused instead on building political and security autonomy.

The Kurds accuse Turkey of backing some of Syria's Islamists and Ankara has often warned it will not allow the establishment of an autonomous Kurdish region on its border.

However, the YPG, the main Syrian Kurdish armed group, has played a key role in fighting the Islamic State jihadist group in north and northeast Syria.

It has also allied with small Arab rebel groups, like Jaish al-Thuwwar, and recently announced the Syrian Democratic Forces coalition, which groups the YPG with Christian and Arab Sunni Muslim forces.

The US-backed alliance has so far mostly been active in the northeastern province of Hasakeh, where it has captured some 200 villages from IS in recent weeks.

- Homs negotiations -

Elsewhere, negotiations are underway between the regime and rebels for the evacuation of opposition forces from the last area they hold in the central city of Homs, the provincial governor told AFP.

Talal Barazi said a meeting was planned for Tuesday "with the goal of reaching a final resolution of the situation in Waer," in the west of Homs city.

Barazi said a deal would "mean the evacuation of the armed men and their weapons, as well as the return of state institutions to the district."

Some 75,000 people currently live in Waer, down from 300,000 before the Syrian conflict began in March 2011.

The Local Coordination Committees, a grassroots activist network, said the meeting on Tuesday was to be held under UN auspices.

Another regional player, the United Arab Emirates, said it is ready to commit ground troops against jihadists in Syria and described Russian air strikes in the country as attacks on a "common enemy".

State Minister for Foreign Affairs Anwar Gargash said the UAE would "participate in any international effort demanding a ground intervention to fight terrorism".

"Regional countries must bear part of the burden" of such an intervention, he said, quoted by WAM news agency.

The UAE is a member of the US-led coalition carrying out air strikes against IS in both Syria and Iraq.

As the jihadists have held out against more than a year of strikes and launched operations abroad including the November 13 attacks in Paris, there have been growing calls for the anti-IS intervention to expand to a ground force.

Russia launched its own strikes in Syria in late September and Iran has reportedly sent hundreds of troops to support Assad.

Critics -- including in the West and Sunni Arab Gulf nations -- have accused Russia of targeting moderate rebels as well as jihadists.

The Observatory said Monday that the Russian strikes have killed a total of 1,502 people, almost a third of them civilians and including 598 Al-Nusra fighters, 419 IS elements and the rest other rebels.

An estimated 250,00 people have been killed in Syria since the onset of the uprising against Assad, which began with demonstrations in March 2011.