BOSTON: Democratic presidential candidate Hillary Rodham Clinton said Thursday she would push for a no-fly zone and safe regions in Syria to address the humanitarian crisis that has spilled out in the Middle East.

"I personally would be advocating now for a no-fly zone and humanitarian corridors to try to stop the carnage on the ground and from the air," Clinton said in an interview with WHDH-TV in Boston.

Russia launched its first airstrikes in Syria on Wednesday against what it said were Islamic State targets. But US officials and Syrian opposition leaders have said the strikes hit areas not controlled by the Islamic State.

Secretary of State John Kerry, who succeeded Clinton at the State Department, has raised concerns that Russia was not targeting the Islamic State but hitting positions of moderate rebels opposed to Syrian President Bashar Assad.

Clinton, following campaign events in the Boston area, said in a separate interview with WCVB-TV that the US should look seriously at the no-fly zone and humanitarian corridors, "but at this point we have to put a lot of pressure on Russia."

Supporters of a no-fly zone in Syria have said it would help stem the flow of refugees and neutralise Assad's warplanes and helicopters. The US has so far resisted the calls.

Clinton's stance puts her at odds with the Obama administration. White House Press Secretary Josh Earnest said Tuesday that the White House wasn't considering a no-fly zone.

"It raises a whole set of logistical questions about how exactly what would be enforced, what sort of resources would be used to actually protect that area," he told reporters aboard Air Force One.

The Syrian civil war, which grew out of an uprising against Assad, has killed more than 250,000 people since March 2011 and sent millions of refugees fleeing to other countries in the Middle East and to Europe.