A U.N. panel is calling for Internet and social media companies to respond to the exploitation of their services by al-Qaida and other extremist groups who use the web to recruit fighters and spout "increasingly horrific propaganda."

The panel recommended in a report circulated Wednesday that these companies brief the Security Council committee monitoring sanctions against al-Qaida, its affiliates and the Islamic State group on measures they are taking to prevent such exploitation.

"A worrisome trend over the past year has been the growth of high-definition digital terror: the use of propaganda, primarily by (the Islamic State group) and its sympathizers, to spread fear and promote their distorted ideology," the panel of experts monitoring sanctions against extremist groups and individuals said in the report to the Security Council.

It said the scale of digital activity linked to the Islamic State group, and to a lesser extent some al-Qaida affiliates, has strategic implications for how the threat from extremists will evolve in the coming years, "not least among the diverse, dispersed and not necessarily demobilized diaspora of foreign terrorist fighters."

In recommending that Internet and social media companies brief the sanctions committee, the panel said: "The scale of the digital threat linked to radicalization, together with the need for concerted action on countering violent extremism, calls for further action by the Security Council."

The Internet's impact on extremist groups is one facet highlighted in the report which covers the global threats posed by al-Qaida, its affiliates, and the Islamic State group.

The panel notes that while these groups pose a threat to international peace and security, "they still kill and injure far fewer people than wars, disasters or road-traffic accidents."

Nonetheless, it said al-Qaida, its associates and the Islamic State group still kill thousands, and in recent months the human cost of attacks by these extremist groups "has been enormous." They have carried out major bombings, assassinations and exploited several million people in Iraq, Syria and to a lesser but no less significant extent in parts of Afghanistan, Libya, Nigeria, Somalia and Yemen, the report said.

The panel said al-Qaida remains overshadowed by the attention paid to its splinter, the Islamic State group, which controls large swaths of Syria and Iraq. The grip of al-Qaida leader Ayman al-Zawahiri on affiliates appears to be weakening, it said, and Al-Qaida's financial position remains precarious compared with that of the Islamic State group.

The panel said the Islamic State group "can claim to have achieved what al-Qaida never did: the building of a territorial entity through terrorist violence."

But it said al-Qaida and its affiliates still pose a serious threat in many parts of the world.

They have become more visible and active in Afghanistan over the past six months, groups associated with al-Qaida have grown in number in South and Central Asia, and Al-Shabab, the al-Qaida affiliate in Somalia, remains a major security threat in the Horn of Africa.

Southern Libya remains "a safe haven" for extremists planning attacks in the Maghreb and Sahel regions and the experts said they have been told of anti-aircraft guns and portable air defense systems in the hands of extremist groups.

Boko Haram has expanded deadly incursions into Cameroon, Chad and Niger but the panel said its ability to maintain long-term control over 20,000 square kilometers of northeastern Nigeria "will require heavier weaponry, access to natural resources and some ability to sustain a local population."

It said the Indonesia-based extremist network Jemaah Islamiyah appears to be reviving and is recruiting professionals, including engineers and information specialists, which could pose "a significant long-term threat" to southeast Asia.