Japan's centre-left government will likely freeze new spending on its joint missile defence system with the United States after the cabinet decided on budget cuts Tuesday, media reports said.

The cabinet's decision would probably delay the deployment of new Patriot Advanced Capability-3 interceptors (PAC-3) until after April 2011, said Kyodo News and other major media, citing unnamed sources.

Defence Minister Toshimi Kitazawa declined to elaborate on the media reports and the cabinet's budget decision but later told reporters: "I cannot say we were able to secure sufficient resources."

"But I believe our basic stance for the defence of our nation was well understood," Kitazawa added. "Details about individual facilities will be decided after those negotiations."

The Sankei Shimbun said the ministry had requested 94.4 billion yen (1.06 billion dollars) for the fiscal year from April 2010 to deploy PAC-3 units at three more Japanese military bases over the next five years.

The government of Prime Minister Yukio Hatoyama, which ended decades of conservative rule in August elections, has tried aggressively to cut spending in efforts to improve debt-ridden government finances.

Foreign Minister Katsuya Okada and other ministers have questioned the past massive spending on the US-developed missile defence system, launched when conservative governments were in power in Tokyo and Washington.

Japan and its long-standing security ally the United States have for years worked jointly on a missile shield of land- and sea-based interceptors against possible attacks, pointing at the threat of communist North Korea.

Japan, officially pacifist since the end of World War II, has since then relied on the United States for defence and nuclear deterrence.

The missile shield in Japan -- made up of PAC-3 surface-to-air missiles and the warship-based Standard Missile 3 (SM-3) -- is now deployed to protect several major cities and had been scheduled for completion by early 2011.