Seoul, South Korea ? North Korea’s weekend missile launches show the communist country is improving its capability and accuracy and are a cause for concern, officials said today.

North Korea launched seven ballistic missiles into waters off its east coast Saturday in a show of military firepower that defied U.N. resolutions and drew international condemnation and concern. It also fired four short-range missiles Thursday believed to be cruise missiles.

South Korea’s Yonhap news agency — citing a South Korean government source it did not identify — reported that five of the seven ballistic missiles landed in the same area, indicating their accuracy has improved.

Australian Foreign Minister Stephen Smith said North Korea’s capabilities were getting better. “If you look at their most recent efforts, the most worrying thing is not their current capacity in terms of distance or scope but how they have improved,” he told the Nine Network today.

“We have seen improvements regrettably in their technology and their approach,” he said.

Saturday’s launches on U.S. Independence Day appeared to be a slap at Washington as it moves to enforce U.N. as well as its own sanctions against the isolated regime for its May 25 nuclear test.

An official, speaking on condition of anonymity citing department policy, said the Defense Ministry was investigating the launches and it would take about a week to complete an analysis.

He also said no signs of additional missile launches had been detected, but more were possible given North Korea warned ships to stay away from the area through July 10.

North Korea’s state news agency did not mention the launches. In Washington, the White House had no immediate comment.

South Korea said Saturday that the missiles likely flew more than 250 miles, apparently landing in waters between the Korean peninsula and Japan.

South Korea and Japan condemned the launches. Britain and France issued similar statements.

Russia and China, both allies of North Korea, expressed concern over an “escalation of tension in the region,” the Russian Foreign Ministry said Saturday in a statement.

Chinese Foreign Ministry spokesman Qin Gang said in a statement that Beijing “hopes all parties will keep calm and restrained and jointly safeguard the overall peace and stability in this region.”

The North has engaged in a series of acts this year widely seen as provocative. It fired a long-range rocket it said was a satellite in early April, and in late May it carried out its second underground nuclear test following the first in late 2006.

The country has also stoked tensions with rival South Korea and last month threatened “thousand-fold” military retaliation against the U.S. and its allies if provoked.

Yonhap also reported that the North is believed to have spent between $34 million and $46 million in test-firing the seven missiles Saturday. It cited no source.

South Korea’s Defense Ministry said it cannot confirm the report.