Serbian officials denied Sunday that the country's security forces used a military-grade sonic weapon to disperse and scare protesters at a huge anti-government rally in the capital. Rights groups claimed that the widely banned acoustic weapon was used during the protest Saturday.

Human rights groups have suggested Serbian authorities used a 'long-distance acoustic device' - but the government has denied it.

Serbian officials are denying that security forces illegally used a military-grade sonic weapon to disperse and scare protesters at a huge anti-government rally