NEW YORK (Reuters) - For the second time in a week, a New York state appeals court has tossed out a weapons possession conviction of a teenager who was searched during a "stop-and-frisk," the New York Police Department's controversial crime-fighting tactic.

In a 3-2 decision released on Tuesday, the court ruled that officers had no justification for searching the 14-year-old boy's backpack where they found a loaded handgun.

The ruling came one week after the same court vacated a weapons conviction for a different teen in another 3-2 decision, finding that officers who stopped and frisked the boy had no "reasonable suspicion" that he had a gun hidden in his jacket.

Last week's ruling drew sharp criticism from Mayor Michael Bloomberg after it became apparent that the boy in question shot a man only months after his earlier arrest.

The two rulings are the latest legal developments in the ongoing battle over the stop-and-frisk strategy in which officers in high-crime neighborhood stop people they consider suspicious.

Police officials have defended the tactic, saying it has helped reduce crime. Critics say the policy disproportionately targets minorities, particularly young black men.

The department conducted more than 685,000 stops last year, and more than 85 percent were either black or Hispanic individuals, according to a recent Reuters analysis.

A class-action discrimination lawsuit against the city brought by four black men who say they were stopped and searched because of their race is pending in Manhattan federal court.

In a statement, the city's top lawyer, Michael Cardozo, said the city would appeal both rulings.

"In each case, the facts gave rise to a reasonable suspicion of danger to the arresting officer," he said. "Interestingly, the police officers' searches also revealed dangerous weapons."

Pat Bath, a spokeswoman for the Legal Aid Society, which represented the 14-year-old, praised the decision for reiterating that a stop-and-frisk without reasonable suspicion "cannot be condoned."

(Reporting by Joseph Ax; editing by Will Dunham and Andre Grenon)