World leaders will make an extraordinary show of support for France by joining a mass rally in Paris this weekend as a wave of global support continued following the bloody end to the Charlie Hebdo attacks' sieges.

Global condemnation poured in as French police killed the Islamist gunmen, with bitter foes Israel and Iran both condemning the slaughter at the satirical newspaper as "terrorism" and even North Korea and Cuba sending condolences.

Israel expressed concern Friday over a "terror offensive" in France, where a gunman stormed a Paris kosher supermarket after the Charlie Hebdo magazine massacre and the killing of a policewoman.

"Israel is following the situation in Paris with concern," Foreign Minister Avigdor Lieberman said in statement.

A meeting between French President Francois Hollande and German Chancellor Angela Merkel planned in Strasbourg Sunday has been postponed after a series of attacks in Paris, said a spokesman for European parliament president Martin Schulz.

Armin Machmer, the spokesman for Schulz, who organized the meeting, said it has been delayed "because of the events" in France, where twin hostage dramas were playing out in the wake of the massacre Wednesday of 12 people at Charlie Hebdo satirical weekly.

A minute's silence will be observed at football grounds throughout France this weekend as a mark of respect for the 12 people killed in the terrorist attack on the Charlie Hebdo satirical newspaper, the French Football Federation (FFF) announced on Thursday.

"Following the terrible attack yesterday at the headquarters of Charlie Hebdo, the French Football Federation has decided to observe a minute's silence in all fields of the Hexagon (France) this weekend, at national and regional matches," the FFF said in a statement.

Rooftop snipers, police in black armored gear and hovering helicopters lent a small French town near Paris's Charles de Gaulle airport where the Charlie Hebdo massacre suspects were holed up the air of a warzone Friday.

Businesses in Dammartin-en-Goele, home to about 8,000 people, shuttered, leaving the streets deserted except for lines of police vehicles and units of heavily armed officers.

Muslim faithful arriving for morning prayers in southwestern France on Friday found racist graffiti scrawled on their mosque, two days after an Islamist attack in Paris left 12 people dead.

The graffiti was written in fluorescent green paint on the gate, trash can and a notice board outside of the mosque in Bayonne, Abderrahim Wajou, the president of the regional Muslim association, told Agene France Presse.

Somalia's Shebab Militants, Al-QaIda's main affiliate in Africa, on Friday praised the massacre at the Charlie Hebdo satirical weekly in Paris as a "heroic" act.

"They made millions of Muslims happy by taking action. Some misguided people claim that freedom of expression was attacked, but that is not the case, and the two heroic people acted accordingly," Radio Andalus, the official mouthpiece of the militants, said in a commentary.

European Union's next scheduled summit on February 12 will focus on how to boost anti-terror efforts in the wake of the deadly Islamist attack on a French satirical weekly in Paris, the bloc's leader Donald Tusk said on Friday.

"Terror has struck in Europe. It is, sadly, not the first time," Tusk said in Riga, the capital of Latvia which assumed EU's rotating presidency on January 1.

The Lebanese intelligence had informed its European counterparts that several jihadist groups linked to organizations in Syria or even in Europe will carry out a huge terrorist act on French territories.

According to As Safir newspaper published on Friday, several intelligence agencies, including that of Lebanon, warned European countries that jihadists will target France with terrorist acts.

Having known ties to jihadist groups is no guarantee a person will be under constant surveillance, experts say, a clue as to how brothers suspected of carrying out the Charlie Hebdo magazine massacre slipped through the cracks.

Finding extremists is easy. What's nearly impossible, intelligence sources say, is tracking every move of all of them, all the time.