AMSTERDAM (Reuters) - Judges at the International Criminal Court (ICC) ordered Libya on Thursday to hand over Muammar Gaddafi's former spy chief, upping the stakes in a row over who has the right to try the deposed strongman's top lieutenants.

The statement placed the Hague-based court on a collision course with Libya's new rulers, who say Gaddafi-era leaders in their custody should face local justice over charges of mass killings and other atrocities.

The ICC Judges said Libya must extradite Abdullah al-Senussi over his alleged role in orchestrating reprisals against the protesters in the 2011 uprising against Gaddafi.

"Libya remains under obligation to comply with the surrender request," the judges said.

They would decide later how to respond if Libya continues to hold Senussi, the judges added. The court has the power to refer the matter to the U.N. Security Council.

The Libya case has become seen as a test of the effectiveness of the 10-year-old court, which relies on the cooperation of member countries to arrest suspects and enforce its orders.

(Reporting By Thomas Escritt; Editing by Andrew Heavens)