Fighting between opposition fighters and President Bashar al-Assad's forces erupted in an oil producing province in eastern Syria, residents and activists said on Sunday, the eve of a parliamentary election the authorities say shows reforms are under way.

Fighters armed with rocket-propelled grenades attacked tank positions in the east of the provincial capital Deir ez-Zor, in response to an army offensive against towns and villages in the tribal area bordering Iraq that has killed tens of people and stopped others reaching supplies and medical care, they said.

"We do not have a death toll because no one is daring to go into the streets," said Ghaith Abdelsalam, an opposition activist who lives near Ghassan Abboud roundabout that has become a flashpoint for the fighting in the city.

"The population has been trapped and anger has been building up," he said, adding the fighting subsided early in the morning after erupting overnight. 

- Reuters