At least 13 persons were arrested by US Federal agents in a sting operation and charged with conspiring to provide material support and resources to the Liberation Tigers of Tamil Eelam, which is on the State Department's terrorist groups list.

Most of the arrested were Canadian or Sri Lankan nationals. Additional arrests were expected, sources said.

Described as supporters of LTTE, some of them were charged with trying to buy sophisticated weapons, including surface-to-air missiles from a black market, for the group's use in the ongoing fight with the Sri Lankan government.

They were allegedly trying to buy 10 Russian-made missiles and 500 AK-47 rifles.

The 54-year-old India-born Nachimuthu Socrates, who was being held pending court appearance later this week, was alleged to have tried to bribe a State Department official  to get LTTE removed from list of foreign terrorist organisations and obtain classified information.

The official was actually an undercover agent.

Assistant US Attorney Mark Rubino said the government viewed Socrates as a flight risk and sought his detention.

Recently unsealed court documents allege that those arrested sought to procure military equipment, communications and indulged in a 'myriad' of other criminal activity. But their target was not the United States, officials said.

Socrates is also alleged to have sought to bribe to get a classified document about US investigation into Tamil Rehabilitation Organisation, charity suspected of being a front for LTTE fundraising.

Socrates was arrested on Monday after a wide-ranging investigation conducted by FBI's Joint Terrorism Force in New York, Connecticut and Illinois. He came to the United States in 1976 and is now a US citizen.

His lawyer, Gerald A Del Piono described him as a businessman and an 'outstanding member of the community who looks forward to resolving these issues as soon as possible'.

Socrates is alleged to have met the undercover agents five times to discuss financial details and given them a cheque of $500 dollars and another $5000 in cash and viewed a purported classified document about LTTE.

Charged for more than 15 years, the LTTE has waged a war of terror, assassinations, and suicide bombings in Sri Lanka [Images] and elsewhere, Roslyn Mauskopf, the US attorney in Brooklyn, said in a statement announcing the charges.

"We refuse to allow the LTTE and its supporters to use the United States as a source of supply for weapons, technology, and financial resources," he said.

Among the arrested persons identified were Sathajhan Sarachandran, Sahilal Sabaratnam, Thiruthanikan Thanigasalm, Nadarasa Yograrasa, Murugesu Vinayagamoorthy, Vijayshanthar Patpanathan, and Thirukumaran Sivasubramaniam.

All were being held without bail and had initial appearances before a federal judge in Brooklyn on Monday, prosecutors said.

Vinayagamoorthy and Socrates were alleged to have met an informant and two people posing as State Department officials numerous times beginning in 2004, offering them $ 1 million in advance to get the LTTE off the terrorism list and to provide US secrets to the group.

Three were accused of traveling from Canada [Images] to the United States to buy anti-aircraft missiles from a person who was an FBI undercover agent.

They, along with another person, were arrested in New York last week.

CNN quoted prosecutors as alleging that the defendants also used several US e-mail accounts to make inquiries about buying weapons; unmanned aerial vehicles; submarine design software; flight lessons; and radio and satellite-navigation equipment.