Syrian artillery pummelled rebel-held areas of Homs on Monday before an expected government announcement that a vote has approved a new constitution proposed by President Bashar al-Assad.
The constitution offers some reforms, but could keep Mr Assad in power until 2028, Reuters reports.
Shells and rockets crashed into Sunni Muslim districts that have already endured weeks of bombardment as the president's forces try to stamp out a revolt that began in March last year.
At least 59 civilians and soldiers are thought to have died in the latest attack.
The International Committee of the Red Cross has failed to secure a pause in the fighting to allow the wounded to be evacuated and desperately needed aid to be delivered.