French President Francois Hollande and Russian leader Vladimir Putin agreed Thursday to coordinate strikes against Islamic State, but differences over Syria's future hampered efforts to bring Russia into a wider alliance to fight the jihadists.

Putin indicated France and Russia would swap data to help identify IS targets in Syria, as opposed to other groups opposed to the country's leader, Bashar Assad.

Berlin police said they carried out two raids targeting Islamists Thursday and arrested two men suspected of preparing to carry out "a serious act of violence representing a danger for the state."

The two individuals, aged 28 and 46, had been "in contact with the Islamist movement," police spokeswoman Patricia Braemer said.

Belgium reduced the terror alert in Brussels Thursday, five days after it was raised to the highest possible level that saw schools and the metro closed, the government's crisis center said.

"We can confirm that the Threat Analysis Coordination Agency re-evaluated the threat level from four to level three," a spokesman for the crisis center, which is part of the interior ministry, told AFP.

Zainabu Ali cradles her infant son Ibrahim in her arms as he sleeps in a three-bedroom house that she shares with about 20 family members in the north Nigerian city of Kaduna.

The family fled Izghe in Borno state in February 2014, when Boko Haram fighters dressed in military uniform stormed the village and slaughtered 106 people, including an elderly woman.

Russia's foreign ministry on Thursday urged nationals currently in Turkey to return home after tensions with Ankara soared over the downing of a Russian warplane.

"In connection with the existing terrorist threats on Turkish territory, we once again recommend that Russian citizens refrain from visiting Turkey, and recommend that Russians who are there for personal purposes return home," the foreign ministry said in a statement.

The two Koreas agreed Thursday to hold a rare high-level dialogue next month, in line with an accord struck in August aimed at easing cross-border tensions, the Unification Ministry in Seoul announced.

A ministry official said the two sides would meet at the deputy minister level on December 11 in the Kaesong joint industrial zone, just inside North Korea.

France's emergency services and military have seen a surge of interest from young people keen to join up after watching the Paris attacks unfold on television.

"During the attacks I saw all these emergency workers helping people voluntarily. I just felt powerless sitting in front of the TV and I said to myself that I wanted to help people as well," music student Simon Chaudemanche told AFP.

Over 200 migrants on Thursday tried to break through barbed wire fences to cross from Greece into Macedonia, which imposed new border restrictions last week, throwing stones at police, AFP reporters said.

At least five of the migrants managed to get across in the assault as the crowd shouted "Open the border" to the Macedonia police ranged in front of them.

Four of the main suspects in the Paris attacks were on a list of radicalized people compiled by Belgium's intelligence services as early as June this year, officials said on Thursday.

The list of 85 individuals included alleged Paris ringleader Abdelhamid Abaaoud, brothers Brahim and Salah Abdeslam and newly named suspect Mohamed Abrini, they said.

Senior military, security and intelligence figures in Nigeria on Thursday questioned President Muhammadu Buhari's December deadline for an end to the Boko Haram conflict, calling it "unrealistic".

The Centre for Crisis Communication, a research and advisory body independent of government, said the deadline was "not tenable" given the continued wave of bombings in the northeast.