North Korea said Saturday it had successfully tested an engine designed for an inter-continental ballistic missile (ICBM)

North Korea said Saturday it had successfully tested an engine designed for an inter-continental ballistic missile (ICBM) that would "guarantee" an eventual nuclear strike on the US mainland.

It was the latest in a series of claims by Pyongyang of significant breakthroughs in both its nuclear weapons and ballistic missile programs.

According to the North's official KCNA news agency, the ground engine test was ordered and personally monitored by leader Kim Jong-Un.

As soon as Kim flagged off the test, "the engine spewed out huge flames with deafening boom", KCNA said.

"The great success... provided a firm guarantee for mounting another form of nuclear attack upon the US imperialists and other hostile forces," Kim was quoted as saying.

Now North Korea "can tip new type inter-continental ballistic rockets with more powerful nuclear warheads and keep any cesspool of evils in the earth including the US mainland within our striking range", he added.

The North's top newspaper Rodong Sinmun featured photos of Kim overseeing the test on its front and second pages Saturday, and said the trial was reportedly conducted at the Sohae Space Centre.

One picture showed Kim looking down from an observation tower as flames were seen over the horizon. Another showed flames streaming down from an engine propped up vertically.   

Military tensions on the divided Korean peninsula have been rising since the North conducted its fourth nuclear test in January, and a long-range rocket a month later that was seen as a disguised ballistic missile test.

The UN Security Council responded with its toughest sanctions to date over the North's nuclear program, and Pyongyang accused Seoul and Washington of spearheading the sanctions drive in New York.

In recent weeks, state media has carried repeated threats of pre-emptive nuclear strikes against both the South and the US mainland.