A US court on Thursday convicted an international arms dealer dubbed the "Prince of Marbella" in a plot to sell machine guns and anti-aircraft missiles to Colombian guerrillas.

Syrian-born Monzer al-Kassar, also known as "El Taous," and an associate face at least 25 years jail after being found guilty in New York of all charges, the US attorney's office said.

These included conspiring to murder US officers, export anti-aircraft weapons and support Colombia's FARC rebels, as well as money laundering.

The conviction marked the downfall of al-Kassar, 63, a veteran weapons tycoon dubbed by the media "Prince of Marbella" for his lavish lifestyle as a longterm resident in Spain.

The acting administrator for the US Drug Enforcement Agency, Michele Leonhart, said the conviction "puts an end to his ability to command a global munitions empire that armed and funded terrorist organizations for decades."

Al-Kassar and his Chilean co-defendant Luis Felipe Moreno Godoy, 60, face at least 25 years in prison on the missiles charge alone, as well as maximum sentences of 15 years for conspiracy to aid terrorists, and 20 years for money laundering.

The United States agreed in extraditing al-Kassar from Spain not to impose death or a life sentences.

The pair were caught in a sting operation as they plotted to sell machine guns, ammunition, and missiles to the Revolutionary Armed Forces of Colombia (FARC), a Marxist group battling the US-backed government there.

Unaware that their contacts were US Drug Enforcement Agency sources, they organized a deal worth millions of dollars in multiple discussions between February 2006 and June 2007, US prosecutors said.

The agents told al-Kassar and Moreno Godoy they needed the weapons to shoot down US helicopters in Colombia. Al-Kassar also offered to provide tons of explosives, guerrilla warfare experts from Lebanon, and other military aid to the FARC, prosecutors said.

US officials say that al-Kassar has been dealing arms since the 1970s to militant groups, including the Palestinian Liberation Front and clients from Central America to ex-Yugoslavia and Iraq.

Al-Kassar was acquitted in 1995 after a three-year trial of supplying weapons used in the hijacking of the cruise ship Achille Lauro, during which a wheelchair-bound US passenger, Leon Klinghoffer, was murdered.

The Anti-Defamation League, a Jewish lobby, welcomed Thursday's conviction.

"We are gratified that justice has finally caught up with Monzer al-Kassar," said ADL director Abraham Foxman.

"The Klinghoffer family has waited far too long to see anyone involved in the horrific killing of their father brought to justice. This is a great day for them, and for all those who have suffered as a result of Kassar's long reign of terror."