(Changes dateline from Madrid, adds not guilty plea)

By Christine Kearney

NEW YORK, June 13 (Reuters) - The Spanish government extradited a suspected Syrian arms dealer to the United States on Friday to answer charges of planning to supply weapons to Colombian rebels.

The United States accuses Monzer al-Kassar, 62, a long-time Spanish resident known as the "Prince of Marbella" for his extravagant lifestyle, of planning to sell arms to the Revolutionary Armed Forces of Colombia (FARC) to protect a cocaine-trafficking business and to attack U.S. interests.

Kassar appeared in U.S. District Court in Manhattan and pleaded not guilty to charges including conspiring to kill American nationals and officers, conspiring to acquire anti-aircraft missiles and providing support to a terrorist organization.

The Spanish government agreed to hand over Kassar after it received assurances from U.S. authorities he would face neither the death penalty nor a life sentence with no chance of parole.

The U.S. Embassy in Madrid said Kassar has been selling weapons since the 1970s to the Palestinian Liberation Front and clients in Nicaragua, Bosnia, Croatia, Iran, Iraq and Somalia.

A year ago, U.S. officials announced that Kassar had been arrested at Madrid airport in Spain and unsealed his indictment. It said he knew the FARC kidnapped U.S. citizens to dissuade American efforts to disrupt the cocaine trade.

The U.S. government has designated the FARC as a foreign terrorist organization. The rebels have been fighting for socialist revolution since 1964 and have at times run large swathes of Colombia.

At the time of his arrest, prosecutors said Kassar had met with two confidential sources working with the U.S. Drug Enforcement Administration at his home in Marbella and discussed the sale of weapons, including assault and sniper rifles and rocket propelled grenade launchers, to the FARC.

Prosecutors say Kassar told the sources the weapons would cost between 6 million and 8 million euros ($8 million to $10.6 million) and offered to send 1,000 men to fight with the FARC against U.S. military officers.

Kassar later met again with the sources at his home and agreed to provide prices for "surface-to-air missile systems for the FARC to use to attack United States helicopters in Colombia," prosecutors said.

Two other men charged in the same case, Tareq Mousa al Ghazi, 61, of Lebanon and Luis Felipe Moreno Godoy, 59, of Marbella, Spain, pleaded innocent last October to terrorism charges in the same case.

They were arrested in Bucharest, Romania and are in U.S. custody awaiting a trial due to begin Aug. 4.

Kassar did not make a bail application and is due to appear again in court on Monday. (Additional reporting by Emma Pinedo in Madrid, editing by Todd Eastham)

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