China appears to have carried out the first flight tests of a previously unseen, stealth fighter jet.

Video clips posted online showed the tailless aircraft moving through the sky accompanied by a J-20 escort.

Experts said the triangular aircraft appeared to be the most advanced design China has yet fielded, although it was too early to determine the capabilities or performance.

Hours later, a second video clip appeared online of flight testing of another, smaller, tailless aircraft.

China has for years been pouring money and innovation into new aircraft in an attempt to break the air-power supremacy of the United States in the Pacific.

Aviation analysts said the disclosure of the two new designs within 24 hours of each other was momentous and showed Beijing’s commitment to the arms race.