Al Qaeda in Yemen has claimed responsibility for the attack on the French satirical newspaper Charlie Hebdo, saying it was ordered by the Islamist militant group's leadership for insults to the Prophet Mohammad, according to a video posted on YouTube.
Gunmen killed 17 people in three days of violence that began when they shot staff in Charlie Hebdo's offices last week in revenge for the publication of satirical images of the Prophet.
One Western source said no hard evidence of a direct operational link to Al Qaeda in the Arabian Peninsula (AQAP) had yet been found.
But it was the first time that a group had officially claimed responsibility for the attack, which was led by Cherif and Said Kouachi, two French-born brothers of Algerian extraction who had visited Yemen in 2011.
In Washington, a State Department spokeswoman said the United States believed the video was authentic but officials were still determining if the claim of responsibility is true.
"As for the blessed Battle of Paris, we...claim responsibility for this operation as vengeance for the Messenger of God," Nasser bin Ali al-Ansi, an AQAP ideologue, said in the recording.
Ansi said the "one who chose the target, laid the plan and financed the operation is the leadership of the organisation", without naming an individual.
He added that the strike had been carried out in "implementation" of the order of overall al Qaeda leader Ayman al-Zawahri, who has urged Muslims to attack the West using any means they can find.
Ansi also gave credit for the operation to slain AQAP propagandist Anwar al-Awlaki, a preacher cited by one of the gunmen in remarks to French media as a financier of the attack.
It was not clear how Awlaki, killed by a U.S. drone in 2011, had a direct link to the Paris assault, but he inspired several militants in the United States and Britain to acts of violence.
The purported claim of responsibility put a new spotlight on a group often cited by Western officials as al Qaeda's most dangerous branch. AQAP has recently focused on fighting government forces and Shi'ite rebels in Yemen, but says it still aims to carry out attacks abroad.
AQAP mocked a huge rally of solidarity for the victims held in Paris on Sunday, saying the shock on display showed the feebleness of the Western leaders who attended.
"Look at how they gathered, rallied and supported each other, strengthening their weakness and dressing their wounds," it said.
Al Qaeda offshoot Islamic State released a video that it said showed interviews with three French fighters in Syria praising the attacks, the SITE monitoring service reported.
One said: "I say to the French people who think that the Islamic State will not reach Europe: With permission from Allah the Almighty, we will reach Europe – all ofEurope."
"JOY AT TORMENT"
SITE also said Nigeria's Boko Haram group had released a video showing its leader welcoming the attacks. "We have felt joy for what befell the people of France in terms of torment, as their blood was spilled inside their country. Allah is Great!" Abubakar Shekau said in the recording, according to SITE.
One Western source described Ansi as an Al Qaeda hawk reputed to have advocated a merger with the even more hardline Islamic State.
Two senior Yemeni sources said Cherif and Said Kouachi had met Awlaki in Yemen and undergone weapons training in the eastern province of Marib. However, aMarib tribal leader denied that they had trained there in 2011 or that Awlaki had been based there.
AQAP's Yemeni leader, Nasser al-Wuhayshi, was once a close associate of al Qaeda leader Osama bin Laden, whose father was born in Yemen, a neighbour ofSaudi Arabia.
Yemeni President Abd-Rabbu Mansour Hadi complained on Wednesday that Yemen had been subjected to a politicised media campaign over the alleged 2011 visit.
"The person reported to have travelled to Yemen to learn in three days how to fire a pistol had been detained and under investigation for two years in France," Hadi said, according to the state news agency Saba. Hadi asked why such suspicious elements had been allowed to travel to Yemen and return home without being questioned.