North Korea told the UN Security Council on Monday that its launch of a spy satellite was legitimate self-defense, rejecting denunciations led by the United States.

Western powers, Japan and South Korea said North Korea violated Security Council resolutions by launching last week's satellite, which the totalitarian state said has already provided images of major US and South Korea military sites.

In a rare appearance at the Security Council, North Korea's ambassador to the United Nations, Kim Song, complained that other countries faced no restrictions on satellites.

"No other nation in the world is in the security environment as critical as the DPRK," said Kim, using the North's official name, the Democratic People's Republic of Korea.

"One belligerent party, the United States, is threatening us with a nuclear weapon," he said.

"It is a legitimate right for the DPRK as another belligerent party to develop, test, manufacture and possess weapons systems equivalent to those that the United States possesses or is developing."

He mocked US charges that satellite technology also helped North Korea hone its missile capacity, questioning whether the United States put satellites into orbit "with a catapult."

The US ambassador, Linda Thomas-Greenfield, rejected North Korea's assertion it was acting in self-defense and said that joint US-South Korean exercises were "routine" and "defensive in nature."

"We intentionally reduce risk and pursue transparency by announcing the exercises in advance including the dates and the activities, unlike the DPRK," she said, adding that the drills did not violate Security Council resolutions.

South Korea's spy agency said that Russia, eager for assistance in Ukraine, helped North Korea on the satellite following a summit between Kim and President Vladimir Putin.

The United States said last month that North Korea has delivered more than 1,000 containers of military equipment and munitions to Russia.

Russia and China, North Korea's main ally, have put forward a resolution, opposed by the United States, to ease sanctions on Pyongyang as part of an effort to encourage dialogue.

Chinese envoy Geng Shuang accused the United States of "further aggravating tension and confrontation" through its military alliance with South Korea.

"If the DPRK constantly feels threatened, and its legitimate security concerns remain unresolved, the peninsula will not be able to get out of the security dilemma and only be caught in a vicious cycle of tit-for-tat aggressive moves," he said.