Syrian forces killed at least five people in an assault on two northern towns on Thursday, activists said, pursuing a military campaign to crush protests against President Bashar al-Assad despite new U.S. sanctions and regional calls to end bloodshed.

The Syrian Observatory for Human Rights said it had the names of five people killed and 16 wounded in morning raids by security forces backed by tanks on Qusair, near the Lebanon border, after overnight protests calling for Assad's removal.

Another activist group, the Syrian Revolution Coordinating Union, said it had identified at least nine people, including a woman and a baby, killed by random gunfire in Qusair.

Around 14 tanks and armoured vehicles also swept into Saraqeb, a town on Syria's main north-south highway that has seen daily demonstrations, and 100 people were arrested by the security forces, residents said by telephone.

Syria's north, particularly Idlib province abutting Turkey, has been one of the hotbeds of the demonstrations across the country for more political freedoms, inspired by popular revolts against repressive ruling elites elsewhere in the Arab world.

Syria has barred most independent journalists since the uprising against 41 years of repressive Assad family rule flared five months ago, making it difficult to verify accounts from both sides of events on the ground.

At least 1,700 civilians have been killed in the unrest, rights groups say, and a series of military assaults on cities and town since the start of Ramadan 10 days ago has sharpened international condemnation.

The United States, saying the world was watching "in horror," imposed sanctions on Wednesday on a Syrian state bank and on Syria's biggest mobile telephone company to target the financial infrastructure propping up Assad's autocratic rule.

Regional powers Turkey, Saudi Arabia and Egypt have all added pressure on Assad to stop the violence although no country has proposed the kind of military intervention being carried out by NATO forces against Libyan leader Muammar Gaddafi.

Syria says 500 soldiers and police have died in the bloodshed, which it blames on armed gangs and terrorists.

WEST WARNS OF TOUGHER UN ACTION

European members of the UN Security Council on Wednesday warned Syria that it could face tougher UN action if Assad continued the onslaught against protesters, while Russia urged Damascus to implement promised reforms as soon as possible.

But Russia and China, both with veto powers in the Council and backed by India, South Africa and Brazil, have vehemently opposed the idea of slapping UN sanctions on Damascus, which Western diplomats say would be the logical next step.

Envoys of Britain, France, Germany and Portugal spoke to reporters after a closed-door session of the 15-nation council convened to assess Syria's compliance with last week's call by the world body for "an immediate end to all violence."

They said the Syrian leadership has ignored that demand.

Despite the worsening bloodshed, there appears little prospect that Western states will put teeth in its sanctions on Assad any time soon by targeting Syria's vital oil industry because of vested commercial interests abroad against doing so.

But Assad is suffering deepening international isolation, with several fellow Arab states recalling their ambassadors this week and pointed calls by Saudi Arabia and Turkey, two regional heavyweights, on him to curb his forces now and launch reforms.

At Wednesday's Council meeting, UN deputy Political Affairs chief Oscar Fernandez-Taranco said that nearly 2,000 Syrian civilians had been killed since March -- 188 since July 31 and 87 on Aug. 8 alone, diplomats at the meeting said.

U.S. Ambassador Susan Rice told reporters that "it would be much, much better for the people of Syria, and Syria would be better off, without Assad." She was echoing comments made last week by White House spokesman Jay Carney.

Russian Ambassador Vitaly Churkin said Moscow had made clear to Damascus that Assad should follow through on reform promises as swiftly as possible.

"They need to have serious reforms as soon as possible, even though we do realise that it takes time, especially in a dramatic situation like this," he said. Asked if he thought the new U.S. sanctions on Syria were helpful, Churkin said, "No."

Syrian envoy Bashar Ja'afari blasted the Europeans, accusing them of misleading reporters about the situation.

"They tried to manipulate the truth and to hide important facts and elements related to the so-called situation in Syria," he said, adding that the Europeans had deliberately ignored Assad's promises of reform and national dialogue.