DAMASCUS  - Syria’s army killed at least nineteen civilians Tuesday in the heaviest shelling of Homs for several days, monitors said, as the international community warned of a humanitarian disaster in the city.

The top human rights representative at the United Nations said the world body’s inaction had “emboldened” Syria’s government to unleash overwhelming force against its own civilians. “The failure of the Security Council to agree on firm collective action appears to have emboldened the Syrian government to launch an all-out assault in an effort to crush dissent with overwhelming force,” said Navi Pillay, High Commissioner for Human Rights.

The assault has been heaviest in the central city of Homs, which has been under a relentless barrage of heavy machinegun fire, tank shells, mortars and rocket-propelled grenades for 10 days.

“The shelling of the Baba Amr neighbourhood began at dawn and is the most intense in five days,” Rami Abdel Rahman of the Syrian Observatory for Human Rights said Tuesday.

“Two rockets are falling a minute on average,” the head of the Britain-based monitoring group told AFP by telephone, citing activists on the ground.

“Six civilians died in the continuous shelling of Baba Amr neighbourhood this morning,” the Observatory said later in an emailed statement.

A video uploaded to YouTube by activists showed a powerful blast striking what they said was Baba Amr, sending flames shooting into the sky and a plume of black smoke up over the rebel stronghold.

Hadi Abdullah of the General Commission of the Syrian Revolution, an opposition activist group, said the shelling of Baba Amr was extremely heavy.

“The situation is tragic. There are pregnant women, people with heart problems, diabetics and, foremost, wounded people who we cannot evacuate,” he said on the phone from the beleaguered city. “On Monday evening three activists entered the town by car transporting bread, baby milk and medicine,” he said. “Their car was hit by a rocket. They all burned to death.

China will not protect the regime of Syria’s President Bashar al-Assad, Premier Wen Jiabao said Tuesday, after Beijing drew international ire for vetoing a UN resolution on the country. Wen’s comments, during an EU-China summit, came after the United Nations’ top human rights representative said the world body’s inaction had “emboldened” the Syrian government to use overwhelming force against its own civilians.

“China will absolutely not protect any party, including the government in Syria,” Wen told reporters in Beijing. He added that the priority now was to “prevent war and chaos” in the violence-hit country.

China and Russia have faced a barrage of criticism for blocking a UN Security Council resolution condemning the bloody crackdown on protests in Syria, including from Arab nations with which Beijing normally has good ties.

On Tuesday, Syrian troops battered Homs in some of the heaviest shelling for days in the flashpoint city, a monitoring group said, as the international community warned of a humanitarian disaster.

The United States called the rare double veto a “travesty”, while one Syrian opposition group said it had handed Assad’s regime a “licence to kill”.

Since the crackdown was launched less than a year ago, more than 6,000 people have been killed, monitors say.