The United Nations urged North Korea on Thursday to stop "any further provocative actions" after the Asian state test-fired what appeared to be two intermediate-range ballistic missiles.

"These types of actions by the DPRK (North Korea) are extremely troubling," said UN Secretary-General Ban Ki-moon's spokesman Stephane Dujarric.

Both missile tests on Thursday failed, a South Korean official said, in a setback for North Korean leader Kim Jong Un in the run-up to next week's ruling party congress.