The United Nations published Monday a report offering guidance and support to countries on tackling "terrorists" who use the Internet to plan attacks, recruit and disseminate propaganda.

"Just as Internet use among citizens has increased in the past few years, terrorist organisations also make extensive use of this indispensable global network," said Yury Fedotov, head of the UN Office on Drugs and Crime (UNODC).

"For example, they may spread propaganda, glorify extremist ideologies and promote violence. They may also recruit, radicalize and incite individuals to commit terrorist attacks by sharing operational instructions and practical guides."

The 148-page report aims to promote a better understanding of the ways extremists use the Internet and to increase international cooperation in order to ensure "effective criminal justice responses to this transnational challenge."

Particular challenges include developing national legislation that help investigators and prosecutors tackle online "terrorist" activity, but while guaranteeing human rights and fundamental freedoms, the UNODC said.