Syria has asked Russia to speed up delivery of S-300 anti-aircraft missiles, concerned about a possible US attack, Syrian Foreign Minister Walid Muallem said in an interview published Thursday.

Speaking to Lebanon's Al-Akhbar newspaper, Muallem said Washington had pledged that US-led air strikes against the Islamic State group would not hit the Syrian army.

"Do we trust this commitment? For now, we realise that President Barack Obama, for domestic reasons, wants to avoid war with Syria," he told the newspaper.

"But we do not know how Obama will act under mounting pressure, and the pressure will only increase if the Republicans achieve a majority in the US mid-term elections, so we have to prepare ourselves."

The interview was conducted before Tuesday's US elections, which saw the Republicans regain control of Congress.

"This is what we explained bluntly to the Russians, and we asked them to use take advantage of the situation and provide us with advanced weapons," he said.

Asked if he was referring to S-300 anti-aircraft missiles, which Damascus has long sought from Russia, Muallem replied: "Yes, and other advanced weapons."

"We will get them and other advanced weapons in a reasonable period," he said.

"The main problem is on the road to a speedy solution, meaning the Kremlin's political approval. It is just around the corner," he added.

S-300 batteries are advanced surface-to-air weapons that can take out aircraft or guided missiles, and Russia's planned sale of the missiles to Damascus has raised international concerns.

Last September, Russian President Vladimir Putin said delivery of the weapons had been suspended "for the moment" without saying why.

His comments came after Israeli Prime Minister Benjamin Netanyahu paid a special visit to Russia to convince Moscow to halt the shipments.

Syria has reportedly paid a deposit of several hundred million dollars for between three to six missile system units.

The entire deal is reportedly valued at around $1 billion.

Russia is a key ally of the Syrian government and has been a staunch supporter of President Bashar al-Assad throughout the uprising that began in March 2011.

It has continued to provide other weapons, as well as credit lines and diplomatic cover to the Syrian government.

Washington last year threatened military action against the Syrian regime, but eventually settled for a deal that saw Damascus give up its chemical weapons arsenal.

Since late September, a US-led coalition has been carrying out air strikes on Syrian territory, but primarily against the Islamic State jihadist group.

Muallem said Washington had given Damascus advanced warning before the strikes began, both through its UN ambassador, as well as via Baghdad and Moscow, and pledged that the bombing would not hit the Syrian army.