The United States is seeking to establish a new military alliance with Russia in Syria that would see the two countries join forces in combating jihadist groups, it has been reported.

The proposal, which was said to have been sent to Moscow this week, would mark a striking change in stated US policy on Syria, with the two super powers having operated largely on opposing sides of the war.

The crux of the deal would see America and Russia launch a coordinated bombing campaign against Jabhat al-Nusra, al-Qaeda's branch in Syria.

In exchange, Russia would be expected to pressure the Assad regime, its key ally, to stop airstrikes against US-aligned rebel groups, an administration official told the Washington Post.

The proposal, which is reported to have been personally approved by President Barack Obama, and supported by John Kerry, the secretary of state, would essentially enforce the creation of informal types of "safe zones", with the US specifying areas that Russia and the Syrian regime would be banned from targeting, rather than giving the precise locations of the US-allied groups.