MADRID, Spain (AP) – Spanish police arrested a Syrian arms dealer with a checkered past that includes allegedly helping Palestinian militants and arming fighters in Iraq and Somalia, this time on American suspicion he supplied weapons to Colombian leftist rebels, Spanish and American officials said.

Monzer al-Kassar, a longtime resident of Spain who has been detained before, was arrested Thursday evening at Madrid airport after he arrived on a flight from the southern city of Malaga, the Spanish Interior Ministry said.

An American official in Madrid said Mr. al-Kassar is accused of supplying weapons to the Revolutionary Armed Forces of Colombia, a rebel army classified in America as a terrorist group. The official spoke on condition of anonymity.

The Spanish ministry said Mr. al-Kassar faces charges at the Federal District Court in New York of conspiracy to provide aid and equipment to a terrorist organization, conspiracy to kill American citizens and officials, conspiracy to acquire and use anti-aircraft missiles and money laundering.

There were no immediate details on extradition proceedings, though Spain and the United States do have an extradition treaty that applies in such cases.

Mr. Al-Kassar, who lives in the resort city of Marbella near Malaga, went before a judge in Madrid on Friday.

He stood trial in Spain in 1995 on charges he supplied assault rifles used by Palestinian militants in the hijacking of the Italian cruise ship Achille Lauro in 1985. He was acquitted.

American Drug Enforcement Administrator Karen Tandy planned to hold a press conference later Friday in New York to discuss the case, the American official said.