VLADIVOSTOK, Russia, Feb. 8 (Xinhua) -- The Russian Defense Ministry will sign a contract this year to buy a dozen advanced stealth fighter jets, Deputy Defense Minister Yuri Borisov said Thursday.

"We are taking the Su-57 for experimental combat operation," Borisov said during a visit to Gagarin, the aviation plant in Komsomolsk-on-Amur.

"This year, we will sign a contract for the first batch of 12 Su-57 fighter jets for the Armed Forces," Borisov said.

The first two planes of the batch may enter into service next year, Borisov said.

Asked about the performance of the new engine for the Su-57, Borisov said it is difficult to judge because there has been only one successful test flight. More trial flights will be conducted over two to three years.

In December 2017, Russia announced its fifth-generation stealth fighter Su-57 had completed its first test flight with a new-generation engine.

The warplane, formerly known as T-50, is being developed by Russia's Sukhoi Company. The single-seat twin-engine jet has super maneuverability and sustained supersonic flight capability.