British authorities must "sharpen up" their response to cases of people traveling to Syria, an influential lawmaker said Monday, after meeting two men whose wives are thought to be there.

Sisters Sugra Dawood, 34, Zohra Dawood, 33, and Khadija Dawood, 30, from Bradford in northern England went missing this month with their nine children aged three to 15 after a pilgrimage to Saudi Arabia.

Israeli Druze on Monday blocked and threw stones at an army vehicle they believed was transferring wounded Syrian rebels for treatment, police said. 

The incident took place as concern grew for the fate in neighboring Syria of members of the Druze minority, traditional allies of President Bashar Assad, who are surrounded by rebels in the country's more than four-year civil war.

European police agency Europol said Monday it was launching a continent-wide cybercrime unit to combat social media accounts promoting jihadist propaganda, particularly those of the Islamic State (IS) group.

The unit, set to start operating from Europol's Hague-based headquarters next month, will comb tens of thousands of social media accounts connected with IS and report them to the companies behind the websites, Europol chief Rob Wainwright said.

The financial assets of one of Syria's wealthiest men -- a cousin of Syrian President Bashar Assad -- will remain frozen in Switzerland, the Swiss Federal Administrative Court said in a statement.

The court rejected an appeal by billionaire Rami Makhlouf to reverse a federal decision blocking an undisclosed amount of money in his Swiss accounts -- which the government says helps "finance" and "support" Assad's violent regime.

The Syrian army has reopened a key oil supply route near Islamic State-controlled Palmyra, as the jihadist group has mined the city's ancient UNESCO-listed ruins.

However, the advance toward the central city from the west, reported by a pro-government newspaper and a monitoring group, and stepped up air strikes, do not indicate an imminent offensive to retake it.

Hundreds of refugees who fled fighting in the Syrian town of Tal Abyad to Turkey were returning home on Monday after a border gate reopened, a Turkish official said.

Kurdish People's Protection Units (YPG) militia ousted Islamic State (IS) jihadists from Tal Abyad after fighting that prompted some 23,000 Syrian refugees to flee into Turkey.

Islamic State group jihadists have mined the spectacular ancient ruins in Syria's Palmyra, an antiquities official and monitor said Sunday, prompting fears for the UNESCO World Heritage site.

The reports came one month after the extremist group overran the central Syrian city.

Foreign Minister Jebran Bassil warned on Sunday of the “imminent wave of terrorism” that is headed towards Lebanon.

He therefore called on all sides “to raise the lines of defenses to protect Lebanon against any foreign threat.”

An international medical aid agency on Sunday voiced alarm over a fuel blockade imposed by the Islamic State group in northern Syria that it says is badly hindering relief efforts.

The IS blockade was having an impact on humanitarian relief activities in a region devastated by more than four years of conflict, said Dounia Dekhili, the Syria program manager for Doctors Without Borders (MSF).

Abu Bakr al-Baghdadi rose from obscurity to lead the world's most infamous and feared jihadist group, but shuns the spotlight for an aura of mystery that adds to his appeal.

The Islamic State group released a slew of photos and videos documenting its offensive that overran a third of Iraq last June, and the many atrocities it carried out.