The number of fighters leaving home to join al-Qaida and the Islamic State group in Iraq, Syria and other countries has spiked to more than 25,000 from over 100 nations, according to a new U.N. report.

The panel of experts monitoring U.N. sanctions against al-Qaida said in the report obtained Wednesday by The Associated Press that its analysis indicates the number of foreign terrorist fighters worldwide increased by 71 percent between mid-2014 and March 2015.

It said the scale of the problem has increased over the past three years and the flow of foreign fighters "is higher than it has ever been historically."

The overall number of foreign terrorist fighters has "risen sharply from a few thousand ... a decade ago to more than 25,000 today," the panel said in the report to the U.N. Security Council.

The report said just two countries have accounted for over 20,000 foreign fighters: Syria and Iraq. They went to fight primarily for the Islamic State group but also the Al-Nusra Front.

Looking ahead, the panel said the thousands of foreign fighters who traveled to Syria and Iraq are living and working in "a veritable 'international finishing school' for extremists," as was the case in Afghanistan in the 1990s.

A military defeat of the Islamic State group in Syria and Iraq could have the unintended consequence of scattering violent foreign terrorist fighters across the world, the panel said. And while governments are focusing on countering the threat from fighters returning home, the panel said it's possible that some may be traumatized by what they saw and need psychological help, and that others may be recruited by criminal networks.

In addition to Syria and Iraq, the report said Afghan security forces estimated in March that about 6,500 foreign fighters were active in the country. And it said hundreds of foreigners are fighting in Yemen, Libya and Pakistan, around 100 in Somalia, and others in the Sahel countries in northern Africa, and in the Philippines.

The number of countries the fighters come from has also risen dramatically from a small group in the 1990s to over 100 today — more than half the countries in the world — including some that have never had previous links with al-Qaida associated groups, the panel said.

It cited the "high number" of foreign fighters from Tunisia, Morocco, France and Russia, the increase in fighters from the Maldives, Finland and Trinidad and Tobago, and the first fighters from some countries in sub-Saharan Africa which it didn't name.

The panel said the fighters and their networks "pose an immediate and long-term threat" and "an urgent global security problem" that needs to be tackled on many fronts and has no easy solution.

With globalized travel, it said, the chance of a person from any country becoming a victim of a foreign terrorist attack "is growing, particularly with attacks targeting hotels, public spaces and venues."

But the panel noted that a longstanding terrorist goal is "generating public panic" and stressed that the response needs to "be measured, effective and proportionate."

It said the most effective policy is to prevent the radicalization, recruitment and travel of would-be fighters.

The panel noted that less than 10 percent of basic information to identify foreign fighters has been put in global systems and called for greater intelligence sharing. As a positive example, it noted that the "watch list" in Turkey — a key transit point to Syria and Iraq — now includes 12,500 individuals.