BEIRUT – Syrian troops bombarded a rebellious suburb of the nation’s capital with tank and artillery shells Friday, killing dozens of people during a particularly bloody few days across the country, activists said.

The violence is part of a fierce government offensive aimed at regaining control of parts of Damascus suburbs where rebels operate. Major world powers were to meet today in Geneva to hash out a political transition plan for Syria, which has been convulsed by more than 15 months of violence.

It’s difficult to get an accurate death toll in tightly controlled Syria, where journalists and human rights groups are either banned or severely restricted.