Israel launched a missile strike near Syria's main northern city of Aleppo early Friday prompting air defences to respond, Syrian state media reported.

Russian military vehicles and attack helicopters surrounded two US armored cars in a tense confrontation in northeastern Syria Wednesday, leaving US troops injured, according to the White House.

Jihadists and allied rebels in northwestern Syria Monday killed at least 12 pro-regime fighters, thwarting their advance, a Britain-based war monitoring group said.

Another 17 pro-regime fighters were wounded while on the jihadist-led side six fighters died, said the Britain-based group Syrian Observatory for Human Rights.

The Israeli army said Monday it had killed four men laying explosives at a security fence along the Israeli-occupied sector of the Golan Heights, adjacent to Syrian-controlled territory.

After Syria's war whisked away the silkworms from his mulberry trees, 65-year-old Mohammed Saud instead turned his idle home workshop into a silk museum to celebrate the ancient craft.

Syria's central bank devalued the Syrian pound on Wednesday giving in to weeks of depreciation on the black market as new US sanctions took effect.

The United States is imposing new sanctions this week against the Syrian government over alleged crimes during the nine-year war, just as Damascus hopes to launch post-conflict reconstruction.

Russian air strikes on northwestern Syria killed a civilian Tuesday, the first such fatality since a ceasefire went into force three months ago, a war monitor said.

Syria's pound hit record lows on the black market Saturday trading at over 2,300 to the dollar, less than a third of its official value, traders said, ahead of new US sanctions.

Six jihadists were killed Wednesday in an explosion that hit their arms depot in northwest Syria while Russian warplanes flew overhead, a war monitoring group said. 

The Britain-based Syrian Observatory for Human Rights did not say if Russia was behind the blast that killed the non-Syrian jihadists allied with the Turkistan Islamic Party, a Uighur-dominated jihadist group.