A new study on foreign fighters linked to al Qaeda and other extremist groups active in the Middle East, such as "Islamic State" (IS), was released to the media on Friday.
According to the findings, some 15,000 foreigners from more than 80 countries were currently operating in Syria and Iraq.
"Numbers [of foreign fighters] since 2010 are now many times the size of the cumulative numbers of foreign terrorist fighters between 1990 and 2010 - and are growing," the report, which was obtained by Britain's newspaper The Guardian and the Associated Press news agency, said.
The report was authored by a panel of experts which monitor al Qaeda and the Taliban and submitted to the United Nations Security Council earlier this week.
It also warned that IS' sophisticated use of the Internet and social media platforms had helped grow its following in a short period of time.
A 'threat for years to come'
Foreign fighters from around the globe "form the core of a new diaspora that may seed the threat for years to come," the report added.
Western nations, which were monitoring the sudden emergency of IS in Syria and Iraq over the past year with great concern, have already felt the influence of this new generation of terrorists on their own soil.
Last week, two alleged converts to radical Islam carried out separate terrorist attacks in Canada, one of which targeted the capital city Ottawa.
Some countries, including Germany, have already passed laws banning any activities related to the infamous Islamist extremist organization, which has hijacked international coverage by beheading captives from countries involved in anti-IS airstrikes.
In September, the United Nations Security Council voted unanimously on a resolution to prevent and suppress foreign fighters.
kms/nm (AP, AFP)