The head of Syria's leading jihadist alliance on Wednesday warned opposition factions in Idlib against taking part in any talks with the regime towards a government takeover of the province.

Hayat Tahrir al-Sham (HTS) chief Abu Mohamed al-Jolani spoke after President Bashar al-Assad warned that he aimed to retake control of the northwestern province on the Turkish border.

The head of HTS, a former Al-Qaeda affiliate, warned fellow jihadists and other opposition fighters in Idlib, Syria's last rebel-held province, against handing over their arms in surrender deals with the regime.

"The weapons of the revolution and jihad... are a red line on which concessions are unacceptable, and they will never be put on the negotiations table," he said.

Jolani's HTS alliance controls around 60 percent of Idlib, while other Turkey-supported rebel groups hold most of the rest.

The regime holds a small patch in the province's southeast.

"As soon as one of us thinks about negotiating over their weapons, they will have lost them," said Jolani in a video posted on his group's Telegram account.

"Just thinking about surrendering to the enemy and handing over weapons is treason."

The Russia-backed regime has this year retaken key territory from rebels through a combination of deadly bombardment and surrender deals, both near Damascus and in the south.

"The people of the north will not allow what happened in the south" to happen again in Idlib, the HTS leader said.

In recent weeks, HTS and other rebel groups have arrested dozens of people, accusing them of collusion with the regime and working towards surrender deals.

"The regime and its allies have tried to follow the same tactic of the so-called 'reconciliation' deals that struck down the southern" provinces of Daraa and Quneitra, he said.

"But your brothers in the north from all factions realised what the enemy's plans were, so we faced them and arrested their leaders, and thwarted the regime's plan," he said.

Analysts say any regime offensive will probably be limited to a small area of Idlib, with a deal between Russia and Turkey likely to determine the fate of the rest of the province.

Turkey has forces deployed at observation points throughout the province.

But, said Jolani, "our people need to realise that the Turkish observation points in the north cannot be relied on to face the enemy."

"Political stances can change in an instant," he said.

Since it started in 2011, with the brutal repression of anti-Assad protests, Syria's civil war has killed more than 350,000 people and displaced millions.

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