North Korea claimed Saturday that it has successfully conducted a ground test of a new engine for an inter-continental ballistic missile, the latest in a series of Pyongyang's claims of progress in its nuclear and missile programs.

North Korean leader Kim Jong-un issued an order to conduct the "jet test of a new type high-power engine of inter-continental ballistic rocket and personally came to the Sohae Space Center to guide the test," the Korean Central News Agency said.

"The great success made in the test provided a firm guarantee for mounting another form of nuclear attack upon the U.S. imperialists and other hostile forces and made it possible to have access to more powerful means capable of reacting to nukes in kind," KCNA quoted Kim as saying.

"Now the DPRK can tip new type inter-continental ballistic rockets with more powerful nuclear warheads and keep any cesspool of evils in the earth including the U.S. mainland within our striking range and reduce them to ashes so that they may not survive in our planet," Kim said.

He also stressed the need to diversify nuclear attack means at a higher level to cope with the ever-more increasing nuclear threats and arbitrariness of the U.S. imperialists and thus decisively counter nukes in kind, KCNA said.

It was the latest in a series of claims of breakthroughs in the North's nuclear and missile programs, including miniaturizing nuclear warheads to fit on an ICBM, mastering missile atmospheric re-entry technology and developing a solid-fuel rocket engine.

The North argued on March 24 that it conducted the successful test of a "solid-fuel rocket engine and its cascade separation" inspected by Kim.

Pyongyang also announced earlier that it has already miniaturized nuclear warheads to fit on an ICBM and mastered missile atmospheric re-entry technology.

These claims came as Pyongyang has been trying to affirm the leadership of its young leader in the run-up to a rare meeting of the ruling Workers' Party set for May.

The KCNA did not specify the name of the tested ICBM. Analysts view it as meaning a KN-14, an upgraded version of the KN-08.

"North Korea appears to be seeking to prove its missile capability in technical stages, as it's hard to show the actual launch of an ICBM," Yang Uk, a South Korean defense specialist, said. "It's apparently asserting that it is capable of attacking the U.S. mainland any time if it wants."

The United States urged the North to refrain from such destabilizing actions and rhetoric.

"We have seen the reports of North Korea's claims to have developed new engine technology for its ICBMs," State Department spokesperson Gabrielle Price said.

"We call on North Korea to refrain from actions and rhetoric that further destabilize the region and focus instead on taking concrete steps toward fulfilling its commitments and international obligations," she said.

(Yonhap)