Syria conflict: Homs arms-depot blast 'kills dozens' Published duration 1 August 2013

media caption Unverified footage shows a huge fireball exploding over Homs city

At least 40 people have been killed in a rocket attack on an arms dump in Syria, the UK-based group the Syrian Observatory for Human Rights has said.

Unverified footage showed a huge fireball shooting into the sky over Homs city.

The rebel Free Syrian Army said it carried out the attack, which struck in a government-controlled area.

President Bashar al-Assad said earlier he was "sure of victory" in the civil conflict that broke out in early 2011.

"If we in Syria were not sure of victory, we would not have had the will to... persevere in the face of more than two years of aggression," he said.

A month ago, government troops launched an offensive to oust rebels from Homs, and recaptured one of the main districts on Monday.

But analysts say the rocket attack shows the rebels are still capable of hitting back.

Witnesses described a series of explosions lasting for more than an hour, suggesting the rockets hit explosives held in the arms depot.

The men filming one of the videos can be heard celebrating with chants of "Allahu Akbar", Arabic for "God is great".

The observatory said the death toll was likely to rise because more than 100 people had been injured in the blast, many of them seriously.

Homs has been a focus of unrest in the two-year uprising against Mr Assad, in which the UN says more than 100,000 people have died.