Mohamed Lahouaiej-Bouhlel, 31, rammed a 19-tonne truck into a large crowd as July 14 fireworks were ending in the French Riviera city.
At least 10 children were among the dead and 50 more were wounded, some of them critically, a hospital official said.
Al-Bayan warned that Western countries "will not be spared from the blows of the mujahideen" no matter how much they increase their security measures.
Earlier, the IS-affiliated Amaq news service quoted a security source as saying the attack was "in response to calls to target nations of coalition states that are fighting (IS)".
IS has called on its supporters living in Europe to carry out lone-wolf attacks on Westerners, publishing a video early this year called "Kill wherever you find them."
French President Francois Hollande said in the wake of the Nice attack that France would strengthen its role in Iraq and Syria, where it is part of a US-led coalition fighting the jihadists.
Prime Minister Manuel Valls said the attacker probably had links to radical Islam, but Interior Minister Bernard Cazeneuve cautioned it was too early to make the connection.
IS also claimed responsibility for the November 13 attacks in Paris which killed 130 people.
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At least 10 children were among the dead and 50 more were wounded, some of them critically, a hospital official said.
Al-Bayan warned that Western countries "will not be spared from the blows of the mujahideen" no matter how much they increase their security measures.
Earlier, the IS-affiliated Amaq news service quoted a security source as saying the attack was "in response to calls to target nations of coalition states that are fighting (IS)".
IS has called on its supporters living in Europe to carry out lone-wolf attacks on Westerners, publishing a video early this year called "Kill wherever you find them."
French President Francois Hollande said in the wake of the Nice attack that France would strengthen its role in Iraq and Syria, where it is part of a US-led coalition fighting the jihadists.
Prime Minister Manuel Valls said the attacker probably had links to radical Islam, but Interior Minister Bernard Cazeneuve cautioned it was too early to make the connection.
IS also claimed responsibility for the November 13 attacks in Paris which killed 130 people.
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