Syrian tanks shelled the city of Hama for a second day on Monday, killing at least four civilians, residents said, in an assault to try to crush protests against President Bashar Al-Assad.

The killings in the city's residential Hamidiyah district brought to 84 the number of civilians reported killed in a tank-backed crackdown on the central Syrian city, where Assad's father crushed an armed Muslim Brotherhood revolt 29 years ago by razing neighbourhoods and killing many thousands of people.

"No one can leave the town because the troops and shabbiha (pro-Assad militia) are shooting at random with machineguns," a resident, who gave his name as Raed, told Reuters by telephone.

Residents said among those killed on Monday was Khaled Adel Al-Sheikh Mossa, whose house was hit in early morning shelling. A roof of another house collapsed and a pharmacy was destroyed. A doctor said a youth died after being shot in the chest.

Syrian tanks also stormed the eastern town of Albu Kamal after a two-week siege, activists in the region said, as the military steps up assaults aimed at subduing dissent in the tribal Deir al-Zor province bordering Iraq's Sunni heartland.

They added that one man, Ibrahim al-Mashadani, was killed as tanks occupied the centre. Residents said tanks surrounded Albu Kamal on July 17 after thousands of people, emboldened by army defections in the town, staged anti-Assad protests.

The latest violence cast a pall over the start of Ramadan.

Residents said at least 29 civilians had been killed in a weekend tank assault on Deir al-Zor, the provincial capital. "The shelling is concentrating on northern quarters. The tanks are pushing toward the centre," a witness told Reuters.

Syrian authorities have expelled most foreign journalists since the anti-Assad protests began in March, making it hard to verify activists' reports or official statements.

The European Union extended sanctions against Assad's government, imposing asset freezes and travel bans on five more people associated with a bloody crackdown on dissent.

EU foreign policy chief Catherine Ashton warned there could be more sanctions unless the Syrian leadership changed course. She welcomed a planned emergency UN Security Council session on Syria later on Monday, saying it was time the world body took "a clear stand on the need to end the violence".

Formal approval of new sanctions, drawn up last week, came after the 27-nation bloc accused Syria of an indiscriminate "massacre" of civilians in the town of Hama at the weekend.

Reed Brody, a spokesman for Human Rights Watch, criticised countries including Russia, China, South Africa, India and Brazil for blocking United Nations sanctions. "These countries have blood on their hands," he said, adding that the Syrian people were paying the price for what was perceived as an "endless" foreign intervention in Libya. -Reuters