Saudi Arabian clerics have declared jihad against Russian and Syrian government forces after urging all Sunni Muslims to join the battle against President Bashar al-Assad.

More than 50 clerics and academics signed a joint statement calling on Sunnis to 'hurry' to war-torn Syria and help to topple Assad's government.

The call came shortly before two rockets were fired at the Russian embassy in Syria's capital Damascus sparking panic among those who had gathered in a show of support for Moscow's intervention in the country.

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More than 50 clerics and academics signed a joint statement calling on Sunnis to 'hurry' to Syria and help to topple President Bashar al-Assad's government

Two rockets struck the Russian embassy (shown in the file picture) in Syria's capital Damascus sparking panic among those who had gathered in a show of support for Moscow's intervention in the country

Hundreds of Syrians had reportedly met this morning to back Russia's air war in Syria before the shells were fired towards the building in the Mazraa neighbourhood.

One witness said both rockets appeared to land in a park close to the embassy compound. A second witness said one of them landed inside the compound. There were no immediate reports of casualties or damage to the building.

Russia's Interfax news agency said two rockets landed in the embassy grounds. It quoted a diplomat at the embassy as saying none of the embassy employees was wounded.

Last night, clerics in Saudi Arabia urged Sunni governments to 'give all moral, material, political and military' in the battled against Assad.

According to Newsweek, the statement said: 'This is a real war on Sunnis, their countries and their identities.

'The holy warriors of Syria are defending the whole Islamic nation. Trust them and support them... because if they are defeated, God forbid, it will be the turn of one Sunni country after another.'

Reuters reports that the clerics who signed the statement are not affiliated to the Saudi government.

This morning, a source revealed how senior Saudi Arabian officials had told Russia's leaders that Moscow's military intervention in Syria will have 'dangerous consequences', escalating sectarian war there and inspiring militants from around the world to join in.

Hundreds of Syrians had reportedly met this morning at the Russian embassy in Damascus (pictured) to back Moscow's air war in Syria before the shells were fired at the building in the Mazraa neighbourhood.

Saudi Arabia's Defence Minister and Deputy Crown Prince Mohammed bin Salman and Foreign Minister Adel al-Jubeir met with President Vladimir Putin (pictured) and Foreign Minister Sergei Lavrov on Sunday

The message, twinned with a pledge of support for moderate foes of Syrian President Bashar al-Assad, Russia's ally, signals Saudi suspicions about Moscow's motives in entering a war in which some 250,000 people have been killed and 11million, or half the population, driven from their homes.

'The Russian intervention in Syria will engage them in a sectarian war,' the source said on Monday, adding that the kingdom 'warns of the dangerous consequences of the Russian intervention'.

'The Saudis will continue strengthening and supporting the moderate opposition in Syria,' he added.

The source said he was citing positions outlined by Defence Minister and Deputy Crown Prince Mohammed bin Salman and Foreign Minister Adel al-Jubeir during meetings with President Vladimir Putin and Foreign Minister Sergei Lavrov on Sunday in the Russian Black Sea resort of Sochi.

The bloodshed in Syria, part of a broader struggle for regional supremacy between Sunni Muslim Saudi Arabia and Shi'ite Iran, has enflamed sectarian divisions across the Middle East and drawn religiously motivated foreign fighters to both sides.

Moscow's intervention has infuriated the kingdom and other foes of Assad who say the Russian air strikes have been hitting rebel groups opposed to the Syrian leader and not just the Islamic State fighters Moscow says it is targeting.

Moscow's intervention has infuriated Saudi Arabia and other foes of Assad who say the Russian air strikes have been hitting rebel groups opposed to the Syrian leader and not just the Islamic State fighters (file picture)

Gulf Arab states suspect the Kremlin's main motive is saving Assad and that counter-terrorism serves as a convenient excuse.

Saudi Arabia, along with Turkey and Qatar, is a leading supporter of the rebels fighting Assad, who is backed by Iran as well as by Russia. But Riyadh is also worried about the rise of jihadist groups such as Islamic State among the opposition.

'The recent escalation will contribute in attracting extremists and jihadists to the war in Syria,' the Saudi source said, adding that the Kremlin's actions would also alienate ordinary Sunni Muslims around the world.

The Saudis urged Russia to help fight terrorism in Syria by joining the existing coalition comprising more than 20 nations that is battling Islamic State militants, the source said.

He also reiterated that Assad must quit as part of a process agreed at a Syrian conference held in Geneva in June 2012 that set out a path to peace and political transition.

A core element of that plan calls for a future Syrian government to be formed by 'mutual consent' of the authorities and the opposition, a stance Washington has said means Assad cannot stay in power.

In remarks to journalists on Sunday about Russia's strikes, Jubeir said he had expressed 'our concerns that these operations could be regarded as an alliance between Iran and Russia'.