At least 15 civilians were killed in the latest Russian and Syrian regime airstrikes in northwestern Syria's Idlib de-escalation zone, a Syrian civil defense group said Thursday.

The Syrian opposition aircraft observatory said areas near Idlib's city center and villages were targeted in the airstrikes.

The White Helmets civil defense group said 15 civilians were killed.

Meanwhile, Turkey has continued its recent reinforcement in the Idlib de-escalation zone. A Turkish convoy including scores of tanks was deployed at different points in Idlib.

The Bashar Assad regime and its allies have intensified air and land attacks on civilian settlements in the Idlib de-escalation zone.

In September 2018, Turkey and Russia agreed to turn Idlib into a de-escalation zone where acts of aggression are expressly prohibited.

But more than 1,800 civilians there have since been killed in attacks carried out by the regime and Russian forces as the cease-fire continues to be violated.

Turkey announced on Jan. 10 that a new cease-fire in Idlib would start just after midnight Jan. 12 but the regime and Iran-backed terrorist groups continued their attacks.

More than 1.5 million Syrians have moved near the Turkish border due to intense attacks over the past year.

Turkey remains the country with most refugees in the world, hosting more than 3.7 million migrants since the start of the Syrian civil war in 2011.