A South African man faces up to 30 years in prison after he was arrested for allegedly selling and trying to smuggle military weapons into the United States.

On Wednesday night, red-faced South African authorities were denying all knowledge of Christiaan De Wet Spies, 33.

Spies, who is believed to have worked for Armscor, was arrested while allegedly trying to finalise a $2,2-million arms deal with an undercover FBI agent on Tuesday at a Manhattan hotel.

Spies, who appeared in a New York court on Wednesday along with 17 other alleged co-conspirators, was allegedly trying to sell former Eastern Bloc and Russian anti-aircraft weapons, anti-tank rockets, rocket-propelled grenade launchers and semi-automatic machineguns to the undercover agent.

He is also being charged with being in the US as an illegal immigrant. Spies and his gang, who are said to specialise in the sale of "heavy" weapons, were variously arrested in New York, Los Angeles and Fort Lauderdale, during an intelligence-driven crime sweep by the FBI and other US authorities.

He and his co-accused face various weapons-trafficking charges, including for a scheme to smuggle rocket propelled grenade launchers (RPGs) and shoulder-fired surface-to-air missiles (SAMs) and other Russian military weapons into the US for sale, and for conspiring to traffic in machineguns and other "similar assault weapons".

According to the charge sheet, the men in fact sold eight such weapons to an informant of the FBI.

The arrests form part of a year-long investigation by the FBI and New York police, whose informant posed as an arms trafficker selling weapons to terrorists. The investigation also included wiretaps and the interception of more than 15 000 calls, the FBI said.

"We began monitoring Spies about a year ago after the informant contacted us. We began monitoring his phone calls in April last year," said FBI spokesperson Special Agent Jim Margolin.

The FBI says that Spies and Armenian Artur Solomonyan, who are believed to be the alleged ringleaders, had several conversations with the informant, who told them his clients were terrorists.

According to the charge sheet, Spies and Solomonyan each face a sentence of 30 years.

Information given to Independent Newspapers on Wednesday night revealed that Spies left for the US nearly two years ago and had been under investigation by US authorities since shortly after his arrival. He is believed to have worked for Armscor for several years, before moving to the US.

Armscor spokesperson Billy Nel, however, said no trace of a Spies having worked at the company could be found.

"We are still searching through company files, but at this stage we have no knowledge about such an employee," he said.

With acknowledgements to Lee Rondganger, Graeme Hosken, Shaun Smillie and the Cape Times.