AMMAN: A main opposition group on Wednesday called on Syrians to boycott an upcoming referendum on a new constitution, saying it was an attempt by President Bashar al-Assad to cover up a crackdown.

"The regime is using this proposal to cover up for its massacres. A constitution cannot be prepared unless all political powers and societal groups in Syria participate in drafting it through an elected assembly," the Local Coordination Committees said in a statement.

Assad has called the referendum for next Sunday and if passed, multi-party elections will be held within 90 days. AGENCIES