WASHINGTON (AFP) - The US government must make public secret papers justifying drone attacks against suspected terrorists, including American citizens, a New York federal appeals court ordered on Monday.

The case was brought by The New York Times and two of its journalists in a Freedom of Information Act (FOIA) case supported by the American Civil Liberties Union.

Their request came following the drone attacks in Yemen that killed Anwar al-Awlaki and Samir Khan in September 2011 and al-Awlaki's teenage son, Abdul Rahman, in October 2011. All three victims were United States citizens either by birth or naturalization.

Judges based their decision on the fact that the information had already been the subject of numerous public statements and speeches, particularly by President Barack Obama, Attorney General Eric Holder and CIA chief John Brennan.

"Whatever protection the legal analysis might once have had has been lost by virtue of public statements of public officials at the highest levels and official disclosure of the DOJ White paper," wrote Judge Jon Newman, referring to the Justice Department.

The decision reverses a judgment of January 2013, which had sided with the US government.

Human rights groups say the drone strike program remains shrouded in secrecy and lacks clear legal limits.

US officials defend the program as carefully regulated and say the strikes have weakened Al-Qaeda's core leadership while reducing the threat of an attack on US soil.