The Syrian army took control of the strategic northwestern crossroads town of Saraqeb on Saturday in the latest gain of a weeks-long offensive against the country's last major rebel bastion of Idlib. Turkey, at the same, is beefing up its forces in the region.

"Army units now exercise full control over the town of Saraqeb," state television reported, over footage of the town's streets, deserted after weeks of bombardment.

The advance came after Turkey sent additional troops two month ago into the region and threatened to respond if any of its military observation posts in Idlib, set up under a 2018 truce, come under attack.

Turkey sends military reinforcements to Syria border

Saraqeb is a strategic prize for the government it seeks to take back control of two major highways that meet in the town. The M5 motorway connects the capital to the country's second largest city Aleppo. Running up from the Jordanian border in the south, it is Syria's longest highway.

The Britain-based Syrian Observatory for Human Rights said on Friday that government forces were in control of the whole extent of the M5 in Idlib province. Only a 30 kilometer (20 mile) section in neighboring Aleppo now remains in rebel hands.

Saraqeb sits at the crossroads with the M4, the main east-west highway in Idlib which links Aleppo with the Mediterranean port city of Latakia, a government bastion. The M4 is still largely controlled by jihadists and their rebel allies.

Turkey reinforced military force in Idlib

Turkey on Saturday reinforced its military presence in Syria's northwestern Idlib province. The Syrian Observatory for Human Rights reported that 430 Turkish military vehicles had crossed into Idlib in the last 24 hours and they were also setting up a new post at Al-Mastoumah on the southern approach to Idlib city. 

Witnesses at the border said convoys of Turkish military vehicles had been crossing into Idlib since Friday, delivering supplies before turning back to return with more. However, the beefing up of Turkish forces has failed to stem the advance by Syrian government forces. 

In Ankara, officials from Turkey and Russia held three hours of inconclusive talks, agreeing to meet again next week. The two countries support opposing sides in Syria's nearly nine-year civil war, but have forged a series of agreements since 2017 aimed at containing the bloodshed. 

"The situation in Idlib was discussed," Turkey's foreign ministry said after the talks. "Steps that could be taken to establish peace on the ground as soon as possible and advance the political process were evaluated."

Experts and diplomats say that Russia is wary of a confrontation with Turkey that could suck Moscow into a military quagmire and cause humanitarian catastrophes in Idlib, so it is likely to take a gradual approach to helping the Syrian government capture the Idlib city. 

Already host to 3.6 million Syrian refugees, Turkey said it can't take more refugees and will do everything to safeguard its country. 

Russia holds key to Idlib's fate as Syrian army advances

Since December, government forces have pressed a blistering assault against the Idlib region with Russian support, retaking town after town despite warnings from Turkey to back off. The violence has killed more than 300 civilians and sent some 586,000 fleeing civilians onto the roads, seeking relative safety nearer the Turkish border.

Iran says ready to mediate between Turkey and Syria

Iran is ready to help Ankara and Damascus resolve their disputes, the Iranian Foreign Ministry said on Saturday.

In a meeting between the visiting United Nations' special envoy for Syria, Geir Pedersen, and Iranian officials, Tehran underlined the importance of resolving issues in Syria through diplomacy, it said on its website.

"During the meeting, Iran reiterated that civilians in Syria should not be used as human shields ... and that Iran is ready to mediate between Turkey and Syria to solve the issue," the website reported.

(With input from AFP and Reuters)