Seoul, Nov 15 : North Korea has successfully conducted ground tests of newly developed solid-fuel engines for a new type of intermediate-range ballistic missile (IRBM), Pyongyang's state media said on Wednesday. The first- and second-stage engines were tested on Saturday and Tuesday to evaluate the technical specifications of the newly developed high-thrust solid-fuel IRBM engines, the Korean Central News Agency (KCNA) said. "The first ground jet tests of the first- and second-stage engines were very successful and the reliability and stability of the already-established Korean-style high-thrust solid-fuel engine designing and manufacturing technologies were clearly verified once again," the KCNA added. "The test provided a sure guarantee for reliably accelerating the development of the new-type IRBM system," it said. The KCNA said the North Korea's General Missile Bureau attached "great significance" to the development at a time the country faces a "grave and unstable security environment" and "vicious" military collusion among its enemies, Yonhap news agency reported. Despite international condemnation, the North Korea has been seeking to bolster its nuclear and missile capabilities that are banned under UN Security Council resolutions. Analysts said the latest tests may be part of such attempts to advance its weapons system in the face of growing trilateral security cooperation among Seoul, Washington and Tokyo. An IRBM, which can fly some 4,000 km, goes beyond the Korean Peninsula and puts the US territory of Guam within range. "It appears to be attempting to develop its weak intermediate-range missiles to increase deterrence against the US," Hong Min, a senior research fellow at the Korea Institute for National Unification, said, noting how the North Korea's intermediate-range missiles had been liquid-fuel types. Solid-fuel missiles are known to be quicker to launch and harder to detect ahead of launch compared with liquid-fuel types. With the North Korea having announced the successful test of the first- and second-stage engines, the recalcitrant regime may attempt to test-launch a solid-fuel IRBM soon as it marks "missile industry day". Earlier this month, the North Korea designated a "missile industry day" to mark the anniversary of its test-firing of the Hwasong-17 intercontinental ballistic missile on November 18 last year. The North Korea is also believed to be preparing to launch a military spy satellite, apparently with technological assistance from Russia following a rare summit between North Korean leader Kim Jong-un and Russian President Vladimir Putin in September. After two earlier launches failed in May and August, the North Korea said it would try again in October. But no such launch has happened, and the North Korea has given no word as to why the launch has been postponed and when it will take place. /IANS