BEIRUT: The Islamic State militant group has expanded its presence in central Syria, seizing control of a town that lies near a highway leading to the capital, Damascus, activists and the group said Sunday.

The Britain-based Syrian Observatory for Human Rights said after intensive clashes with government troops, IS forces captured Mahin in the central province of Homs on Sunday and were now pushing their way northwest toward the majority-Christian town of Sadad. The town is home to Syria's Assyrian Christian minority and the ancient language of Aramaic is still spoken there.

Mahin is 25 kilometers (15 miles) east of the highway that links the central province to Damascus. The town also houses a large military complex and arms depots— and was scene of intense clashes between government troops and al-Qaida's affiliate in Syria in 2013 before the government recaptured it.

The capture of Mahin, and the push toward Sadad, marks a new advance of the Islamic State group in central Syria. The group's strongholds lie in northern and eastern Syria; but the group has, as recently as May, established a presence in Homs, seizing the ancient city of Palmyra and then another village to the west.

The new IS expansion comes despite concerted Russian airstrikes in Syria, which Moscow says target IS and other terrorist groups. For the most part, the Russian airstrikes, in their fifth week, have targeted Western-backed rebel groups and other Islamist groups. IS militants have also made recent gains in Aleppo, seizing villages from other rebel groups and controlling a section of a strategic highway that serves as a supply route into government-controlled areas of Aleppo.

The Islamic State internet radio broadcast, Al-Bayan, said the group took control of large arms depots in Mahin after a suicide bomber blew himself up at a government checkpoint outside the town, opening the way for its fighters to advance.

The Observatory reported airstrikes on Mahin, following IS control of the town.

Also on Sunday, Syria's foreign minister said "important" points were made during international talks seeking to revive a moribund political process and end his country's civil war, now in its fifth year.

But Walid al-Moallem said negotiators failed to convince his government's foes to curb their support for "terrorism."

Al-Moallem's comments came after his meeting with UN special envoy Staffan de Mistura, who arrived in Damascus Sunday to brief him on the details of the international talks in Vienna.

The Vienna meeting, which ended Friday, brought together the United States, Saudi Arabia and Turkey, which back the Syrian opposition, and Syrian President Bashar Assad's two key allies, Iran and Russia.

Neither the Syrian government nor the opposition was directly represented at the talks.

Syria's government refers to the entire armed opposition as "terrorists." It blames Saudi Arabia and Turkey of arming them and fuelling terrorism in Syria.