[DAMASCUS] Syrian President Bashar al-Assad on Sunday said his enemies have increased support for rebels fighting his regime as loyalists backed by Russia and Iran push an offensive to regain lost territory.
His remarks came as the Syrian Observatory for Human Rights said 18 civilians were killed and 40 wounded in "probable" Russian air strikes on a northwestern town held by a rebel alliance.
The Britain-based Observatory also reported that the Islamic State group had murdered more than 3,500 people in Syria, including 2,000 civilians, since declaring its "caliphate" last June.
The latest developments came as Britain pressed efforts to widen its participation in a US-led air coalition battling IS in Iraq to include Syria.
Defence Secretary Michael Fallon said his government was intensively lobbying the opposition Labour party to support air strikes in Syria, two years after it had blocked that option.
In remarks during talks with a senior Iranian official in Damascus, Assad spoke of "important gains by the Syrian army in the fight against terrorism, with the support of its friends led by Iran and Russia." State news agency SANA also quoted him as saying that these gains had "pushed certain countries hostile to Syria and who pretend to fight terrorism to... increase their financing and arming of terrorist groups".
Assad did not identify any country by name but since the outbreak of the Syrian conflict in March 2011, he has accused Turkey and Gulf nations of arming his mainly Sunni opponents.
Assad's regime, dominated by the Shi'ite Alawite sect, launched a key offensive to retake areas seized by opponents after Moscow began in late September an air war in support of the government.
Iran, the region's main Shi'ite power, has also backed Assad, including with the reported deployment of hundreds of "military advisers" to bolster regime forces.
Following the November 13 Paris attacks which killed 130 people and were claimed by IS there have been increasing calls by French leaders on their allies to step up the fight against the jihadist group.
On Thursday, French Defence Minister Jean-Yves Le Drian called on Britain - which is already taking part in US-led air strikes on IS in Iraq - to help "win this war".
Mr Fallon told the BBC that his government had been pressing the opposition Labour party to vote yes on launching air strikes on Syria.
"We've been talking to Labour MPs all week," he said, but the government had "not yet" secured enough support to be sure of winning such a vote.
British Prime Minister David Cameron said Saturday that IS was a threat to Britain and conducting air strikes in Syria would be the "right thing for Britain to do".
He was speaking as thousands of people took to the streets of London to protest against military action in Syria.
Britain, which was also hit by terror attacks, remains deeply scarred by its former interventions in Afghanistan and Iraq.
Thousands also protested against military action in Syria on the streets of Madrid, amid fears by many Spaniards that it would make their country a target for militants.
A poll published Sunday in Spain's El Mundo newspaper showed that Spaniards are divided on joining anti-IS strikes, with 54 per cent opposed.
In Germany, army chief of staff General Volker Wieker told Bild am Sonntag newspaper his country is planning to deploy 1,200 troops to help France in the battle against IS but not join air strikes.
The coalition already had "sufficient forces and means", he said when asked why Germany had shied away from participating in air strikes in Syria.
Initially an anti-regime uprising, the Syrian conflict has evolved into a multi-front war in which the regime, jihadists including IS, secular rebels and a range of ethnic militias are battling for territory.
More than 250,000 people have died in the fighting and millions have been forced from their homes.
Elsewhere, Turkey said the body of a Russian pilot shot dead in Syria after his plane was downed shot down last week by Turkey had been retrieved and will be returned to Moscow.