Syria's chief-of-staff has declared a wide-ranging ground offensive by Syrian troops, a day after government forces advanced in a multipronged attack backed by Russian airstrikes and cruise missiles launched from the Caspian Sea.

Gen. Ali Ayoub says the Russian strikes have facilitated an expanded military operation to eliminate "terrorists." The Syrian government refers to all armed opposition against President Bashar Assad as terrorists.

Syrian activists said government troops pushed Thursday into rural parts of Latakia province.

Activist Ahmad al-Ahmad said on Wednesday, fighting that focused on rural Hama and Idlib province in northwest sparked intense clashes, with rebels repelling government troops from at least one village.

Meanwhile, the Britain-based Syrian Observatory for Human Rights said Russian airstrikes in Idlib killed at least seven civilians on Wednesday.