WASHINGTON, Jan 23 (Reuters) - A U.S. appeals court on Monday upheld the dismissal of a lawsuit by an American citizen who claimed he had been illegally detained and tortured at a military jail in South Carolina.

The ruling found the claims by Jose Padilla, who has been convicted on terrorism charges, to be without merit. It held he had no right to sue for certain alleged constitutional violations and concluded the judiciary cannot review such sensitive military decisions.

Padilla, a former Chicago gang member and a Muslim convert turned al Qaeda recruit, sued a number of former and current high-level government and military officials, including former U.S. Defense Secretary Donald Rumsfeld and the current Defense Secretary, Leon Panetta.

Padilla sought a declaration that his designation as an enemy combatant, his military detention and his treatment in custody were unconstitutional. He sought nominal damages of one dollar from each defendant.

The American Civil Liberties Union, which represented Padilla, denounced the ruling.

"By dismissing this lawsuit, the appeals court handed the government a blank check to commit any abuse in the name of national security, even the brutal torture of a U.S. citizen on U.S. soil," said Ben Wizner, an ACLU attorney who argued the case.

A federal judge in South Carolina dismissed the lawsuit last year and the U.S. Court of Appeals for the Fourth Circuit, based in Richmond, Virginia, agreed.

It said that Padilla could not use a lawsuit seeking money damages to review sensitive military decisions about national security, and that the courts were not the proper forum for his objections to policies adopted by the government and the U.S. Congress that resulted in his detention and interrogation.

While designations of persons as a special threat to national security may be subject to various checks and certain legal proceedings, they cannot be reviewed by the judiciary in a lawsuit seeking money damages, the appeals court held.

Judge J. Harvie Wilkinson said in the opinion that allowing such lawsuits "would expose past executive deliberations affecting sensitive matters of national security to the prospect of searching judicial scrutiny."

He said it would inhibit future discussions if top government officials faced prolonged civil litigation and potential personal liability.

Padilla was taken into custody in Chicago in May 2002 after arriving at O'Hare International Airport from Pakistan via Switzerland.

President George W. Bush declared Padilla an enemy combatant a month later, saying he possessed valuable intelligence about al Qaeda. Padilla was taken to a Navy jail in South Carolina and held there for more than three years.

Padilla was convicted in 2007 in a U.S. court in Miami on charges of conspiracy to murder, kidnap and maim people abroad, conspiracy to provide material support for terrorism and providing material support for terrorism.

A different U.S. appeals court ruled in September that the 17-year prison sentence that Padilla received was too lenient and ordered that he be re-sentenced.

(Reporting by James Vicini)

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