SEOUL (South Korea) - A BARRAGE of ballistic missiles that North Korea test-fired over the weekend may have included a new type of Scud missile with an extended range and improved accuracy that poses a threat to Japan, a South Korean newspaper reported on Monday.

On Monday, South Korea's mass-circulation Chosun Ilbo newspaper reported the launches were believed to have included three Scud-ER missiles with a range of up to 1,000 kilometres.

The paper said the Scud-ER has a longer range and better accuracy compared with previous Scud series so is 'particularly a threat to Japan'. Tokyo is about 1,160 kilometres from the base on North Korea's east coast from where the missiles were fired. Some other parts of Japan are closer, well within the range of a Scud-ER.

Scuds are single stage, liquid-fuelled missiles, originally developed in the former Soviet Union, and generally known for poor accuracy. Ballistic missile programs in Pakistan and Iran were built on Scud technology.

The Chosun Ilbo, citing a government source it did not name, said the other four missiles were two Scud-C missiles with a range of 500 kilometres and two medium-range Rodong missiles that can travel up to 1,300 kilometres.

Five of the seven missiles flew about 420 kilometres from an eastern coastal launch site and landed in one area, meaning their accuracy has improved, the paper said. South Korea's Defence Ministry said it could not confirm the report, saying details of the launches were still under investigation.

One Defence Ministry official told The Associated Press on Sunday that the missiles appeared to have travelled about 400 kilometres, meaning that key government and military facilities in South Korea were within range. The official spoke on condition of anonymity citing department policy.

North Korea has long-range missiles as well. The Taepodong-2 has a potential range of more than 6,700 kilometres, putting Alaska within striking distance.

The country is believed to be developing a missile with an even longer range that could potentially put the US west coast, Hawaii, Australia and eastern Europe within striking distance.

The North has warned ships to stay away from a large area off the east coast until July 10, leading to concerns more missiles could be fired. -- AP