Syrian President Bashar al-Assad will be removed by force if the peace process fails, Saudi Arabia's Foreign Minister has said.

"Bashar al-Assad will leave - have no doubt about it," Saudi Arabia's Foreign Minister Adel al-Jubeir told CNN. "He will either leave by a political process or he will be removed by force."

Saudi Arabia has sent troops and fighter jets to a Turkish military base ahead of a possible ground invasion of Syria.

Mr Jubeir said Saudi Arabia is prepared to contribute ground troops to the fight in Syria, but only as part of a US-led coalition.

There were reports of Royal Saudi Air Force F-15 jets arriving at Incirlik Air Base in Turkey on Saturday morning (AFP/Getty Images)

He added: "We will push as much as we can to ensure that the political process works. But if that doesn't work, it will be because of the obstinance of the Syrian regime and that of its allies.

"And should that prove to be the case, then it becomes clear that there is no option to remove Bashar al-Assad except by force."

Bashar al-Assad and Vladimir Putin (GETTY IMAGES)

On Sunday, he told a press conference in Riyadh that previous efforts to prop up Assad by Iran had failed.

"Now, [President Assad] has sought the help of Russia, which will fail to save him," he added.

Drone video shows levels of devastation in Homs, Syria

The Foreign Minister's comments come as Syrian government forces, backed by Russian air strikes, have taken rebel ground near Aleppo and are poised to advance on the Isis stronghold of Raqqa province.

The move could be aimed at pre-empting any Saudi plans to send ground forces to fight Isis in Syria.