Muscat and Damascus agreed to work together to end Syria's brutal war, official media reported, as the Syrian foreign minister Thursday made his first Gulf visit since the conflict erupted in 2011.

Foreign Minister Walid Muallem met Oman's chief diplomat Yussef bin Alawi to discuss "several regional and international topics of common interest," the official Omani news agency ONA said.

Syrian government forces backed by Hizbullah have advanced from different directions in the mountain resort of Zabadani near the border with Lebanon, Syrian state media reported.

Syrian opposition groups have accused the government and Hizbullah of displacing thousands of Sunnis from areas along the border with Lebanon and preventing them from returning to their homes.

Islamic State jihadists seized control of a key town in the central Syrian province of Homs overnight after heavy clashes with forces loyal to President Bashar Assad, a monitor said on Thursday.

The violent group started the attack on Wednesday morning when three suicide bombers targeted pro-regime checkpoints at entrances to the city, according to the Britain-based Syrian Observatory for Human Rights.

A U.S. armed drone bombed a target in Islamic State-controlled northern Syria on Wednesday, in the first such air strike by a U.S. aircraft after taking off from Turkish territory, a Turkish official told AFP.

"A U.S. drone today carried out one air strike in Syria near Raqa," said the official, referring to the town in northern Syria the IS group sees as its capital. 

Syrian rebel groups allied with al-Qaida fought on Wednesday to advance on a key military headquarters near President Bashar Assad's coastal heartland, a monitor said.

The Islamist rebels, including fighters from Central Asia and Chechens as well as jihadists from Syria's al-Qaida branch al-Nusra Front, were pressing an advance on the village of Jureen, the Syrian Observatory for Human Rights said.

Iran said Wednesday it will submit a new peace plan for war-ravaged Syria to the United Nations on the back of an international shift in favor of a political settlement.

Deputy Foreign Minister Hossein Amir-Abdollahian said the plan, drafted after "detailed consultations" between Damascus and Tehran, was an amended version of an Iranian initiative presented last year.

Syria's opposition National Coalition has accepted an invitation to hold talks in Russia with Foreign Minister Sergei Lavrov, whose country is a key ally of the Damascus regime, a coalition member said Wednesday.

Its deputy leader Hisham Marwa told AFP coalition chief Khaled Khoja received an invitation at the start of August to visit Moscow.

Ankara on Wednesday appointed a new army chief as Turkey wages a dual offensive against Kurdish militants and Islamic State (IS) jihadists. 

Land Forces commander Hulusi Akar, 63, takes over as chief of staff from retiring General Necdet Ozel as part of a major shake-up of the army's top brass. 

Two German-speaking jihadists claiming to belong to the Islamic State militant group threatened Germany with attacks in an execution video broadcast online Wednesday.

The five-minute clip shows the men use assault rifles to kill two bound and kneeling male hostages in the Syrian ancient city of Palmyra, which IS fighters took in May.

Turkey on Wednesday announced that it was ready to begin a "comprehensive" fight against Islamic State (IS) jihadists in Syria alongside the United States, after a months of staying on the sidelines of the U.S.-led coalition.

Ankara, long criticized for failing to stop the flow of jihadists to-and-fro across its border with Syria, has so far concentrated an almost two-week "anti-terror" campaign on the bombing of Kurdish militants.