An estimated 6,000-10,000 fighters are operating under the Daesh terrorist group in Iraq and Syria, the United Nations counterterrorism chief said Wednesday, calling on member states to maintain gains against the threats by the terrorist group to prevent its expansion.

Speaking at a Security Council briefing, Vladimir Voronkov, under-secretary-general of the United Nations Counter-Terrorism Office, said: "During the reporting period, the group maintained its ability to launch attacks at a steady rate, including hit-and-run operations, ambushes and roadside bombs in both countries. It also continued to attack government forces and civilians with the apparent aim of instigating panic and increasing pressure on the authorities."

He warned that the group is known for its ability to regroup and even intensify its activities following major defeats.

"Military counterterrorism operations may be necessary, but comprehensive measures with a strong focus on prevention are required to address the dynamics that fuel the appeal of terrorism," he added.

Last week, Daesh leader Abu Ibrahim al-Hashimi al-Qurayshi was killed after he blew himself up during an operation by U.S. forces in northern Syria. Al-Qurayshi, whose real name was Amir Muhammad Saeed Abdul Rahman al-Mawla, had taken over after the U.S. killed Abu Bakr al-Baghdadi in 2019.

Voronkov stressed that it is crucial to build on the momentum following the death of al-Qurayshi.

"Now is the time to address the grievances that Daesh and other terrorist groups exploit with their propaganda to attract new followers. We must focus on restoring human dignity, trust and social cohesion," he said.

"This must start with addressing the desperate situation in displacement camps and detention facilities across Syria and Iraq."

Daesh was back in the headlines during the recent weeks, a reminder of a war that formally ended three years ago but continues to be fought mostly out of sight.

Daesh lost its last patch of territory near Baghouz in eastern Syria in March 2019. Since that time, it largely went underground and waged a low-level insurgency, including roadside bombings, assassinations and hit-and-run attacks mostly targeting security forces. In eastern Syria, the militants carried out around 342 attacks over the last year, many of them on the U.S.- backed YPG terrorists, according to the Britain-based Syrian Observatory for Human Rights (SOHR).