Syrian president Bashar al-Assad raised the prospect of opening a front against Israel and said Russia was committed to supplying his regime with advanced missiles, in an interview broadcast overnight.

Washington said such a move by Moscow would only prolong the conflict between government forces and Assad's foes in Syria, where activists say more than 94,000 people have been killed since March 2011.

"There is clear popular pressure to open a new front of resistance in the Golan," Mr Assad told a Hezbollah TV channel.

"There are several factors, including repeated Israeli aggression," he said, referring to reported Israeli air strikes on Syria.

"We have informed all the parties who have contacted us that we will respond to any Israeli aggression next time."

There was no immediate comment on Mr Assad's remarks from Israel, which seized the Golan Heights from Syria in the 1967 Six-Day War.

The armistice line has remained calm since then, despite some spillover from the Syrian conflict.

Assad hints Russian missiles have already been delivered

Mr Assad, whose forces are battling alongside Hezbollah fighters to recapture the key town of Qusayr near the border with Lebanon, said he was "very confident" of victory.

"There is a world war being waged against Syria and the policy of (anti-Israeli) resistance... (but) we are very confident of victory," he said.

Earlier Syrian state television said the Arjun district in northern Qusayr, one of the few remaining rebel strongpoints, had been taken, leaving rebels there little chance to escape.

Mr Assad, who belongs to the Alawite offshoot of Shiite Islam, appeared to imply in the interview that Russia has already delivered some of the promised ground-to-air S-300 missiles.

"All the agreements with Russia will be honoured and some already have been recently," he said.

Moscow, the Assad regime's most powerful ally, has yet to confirm if it has already sent S-300s to Syria, but it announced this week it intends to honour its contract.

US National Security Council spokeswoman Caitlin Hayden declined to comment on Mr Assad's suggestion that S-300s have been delivered.

"Our concerns about Russia's continued support for the Syrian regime through the provision of arms and access to Russian banks are well known," she said.

"Providing additional weapons to Assad - including air defence systems - will only prolong the violence in Syria and incite regional destabilisation."

On Tuesday Israeli defence minister Moshe Yaalon said his country "will know what to do" if the missiles were delivered.

But on Thursday, another minister indicated Israel would only act to prevent the missiles being used against it.

"The problem arises when these arms fall into other hands and could be used against us. In that case, we would have to act," energy and water minister Silvan Shalom said.

The Jewish state has already launched several air raids inside Syria this year, reportedly targeting convoys transporting weapons to its arch-foe Hezbollah.

Russia has defended its arms shipments to Syria, with deputy foreign minister Sergei Ryabkov saying the missiles were a "stabilising factor" which could deter foreign intervention.

UN paves way for peace talks in Geneva

On the diplomatic front, the United Nations said a preparatory meeting for a proposed international conference on the Syrian conflict would take place in Geneva next week.

"We can confirm that on 5 June, 2013 in Geneva, US, Russian and UN officials will hold a three-way meeting to further the preparations for the international conference on Syria envisioned under the US-Russian initiative," it said in a statement.

Syria's opposition National Coalition, meeting in Istanbul, earlier said it would not take part in the peace initiative dubbed Geneva 2 "so long as the militias of Iran and Hezbollah keep up their invasion".

The declaration came as the Coalition appealed for the rescue of 1,000 citizens wounded in Qusayr, which Mr Assad's forces have been trying to seize back in an all-out offensive since May 19.

"Qusayr has been under constant bombardment," said a Coalition statement, and a "large number of civilians living in the area have been injured due to the assault launched over two weeks ago on the city."

The Coalition insists any negotiations with the regime must lead to Mr Assad's resignation, a position Russia has criticised as unrealistic.

AFP/ABC