TOKYO (Reuters) - Japan on Thursday (June 23) began to examine the suspected nose cone of a North Korean rocket that washed up on a Japanese beach hoping to glean information on the reclusive state's ballistic missile programme a day after it test-launched two more missiles.

The red, white and blue item, believed to be half of the nose cone designed to protect the rocket's payload, was found on a beach in western Japan last Thursday and is suspected to come from a long-range, three-stage rocket fired by North Korea on Feb 7 that flew over Japan's southwest Okinawa island chain.

The South Korean authorities recovered the other half. "We will analyse the materials and the level of technology used," a Japanese Ministry of Defence official said after the part was delivered by truck to the ministry.

The pockmarked 75kg part, almost 2m wide and over 1m wide, lay on a blanket and blue tarpaulin in a forecourt at the ministry.

The February launch, which North Korea said put a satellite into orbit hundreds of kilometres above Earth, came just weeks after Pyongyang carried out a nuclear bomb test, both in defiance of UN resolutions and sanctions.

Concern that North Korea is getting closer to perfecting its ballistic missile technology heightened on Wednesday after it fired what appeared to be two intermediate range ballistic missiles.

While the first was deemed a failure, the second rocket climbed to more than 1,000km before plunging into the Sea of Japan 400 km down range from the launch sight.

"For Japan, it raises deep concern over our national security," Japan's top military commander, Admiral Katsutoshi Kawano, said on Thursday in Tokyo.

The next step for Pyongyang could be to miniaturise its nuclear bomb technology into a warhead that fits on the missile.

North Korean leader Kim Jong Un said after supervising Wednesday's launches that the country now had the capability to attack US interests in the Pacific, official media reported.