Syria's Interior Ministry says the sleeper cell behind a deadly church explosion near Damascus belonged to the Islamic State group.

Syrian authorities on Monday announced arrests over a suicide blast targeting a church blamed on the Islamic State group, as President Ahmed al-Sharaa vowed those involved in the "heinous" attack would face justice.

Sunni extremist group Saraya Ansar al-Sunna claims responsibility for a Damascus church bombing that killed 25, challenging the Syrian government's assertion of ISIS involvement.