China says two test pilots were killed while developing its first aircraft carrier fighter wing, a rare admission of a setback in the hugely popular program.

In a report last month that went largely overlooked, the official Xinhua News Agency said President Xi Jinping signed an order awarding honorary titles to all pilots in the first squadron to conduct take-off and landing tests aboard the Liaoning, China's only aircraft carrier.

It said two pilots sacrificed their lives during the tests but gave no details.

China announced it had begun flight tests on the Liaoning in late 2012, spurring a wave of patriotic pride in the country's growing capabilities. Chinese pilots fly the J-15 fighter-bomber, a copy of Russia's Sukhoi Su-33. China spent a decade refurbishing the carrier bought from Ukraine.