North Korea crossed a “major threshold” towards developing a nuclear missile capable of striking the US when it successfully launched a rocket into space on Wednesday.

The UN Security Council “condemned” the thinly disguised missile test after meeting in emergency session last night. America led the denunciation of the unexpected launch of the Unha-3 rocket from Sohae Space Centre, calling it a “highly provocative act that threatens regional security”. The White House said it was “yet another example” of North Korea’s “irresponsible behaviour”.

By conducting the test, North Korea has broken United Nations Resolution 1874, passed unanimously in June 2009, which bans the regime from conducting “any launch using ballistic missile technology”.

Immediately after lifting off from a site north of the capital, Pyongyang, the rocket was detected by a South Korean destroyer equipped with Aegis, an advanced radar and anti-missile system. Debris from the first stage of the launch fell into the sea off the South Korean coast. The rocket, which North Korea said was designed to place a satellite into space, then passed over Japan’s Okinawa Prefecture. The second stage fell into the Pacific east of the Philippines, with aerospace experts saying the launch appeared to have been a success.

The US and Asian governments believe that North Korea’s space programme is a cover for the development of long-range ballistic missiles that could ultimately carry nuclear warheads. The country already has a small arsenal of nuclear bombs, testing devices in 2006 and 2009.

But its scientists are not yet able to make nuclear warheads for missiles. The Unha-3 rocket is a modified version of the Taepodong-2 ballistic missile. Experts believe that tests of this kind will help North Korea to master the technology needed for nuclear-armed missiles, with ranges of about 5,000 miles – sufficient to hit the US. “The North has crossed a major threshold in terms of mating an ICBM [intercontinental ballistic missile] with a nuclear weapon,” said Victor Cha, a Korea specialist at the Centre for Strategic and International Studies in Washington. “They still have other technological thresholds to cross, but this was undeniably a major one.”

A beaming female presenter on state television announced the launch to jubilant North Koreans. Ham Myong-son, a resident of Pyongyang, told Associated Press that he felt “proud to have been born a Korean”, adding that the occasion showed his country’s “cutting edge science and technology”.

The regime had refrained from trumpeting the test in advance, probably because the last time it did so in April, the rocket suffered catastrophic failure and plunged into the ocean barely 90 seconds after lifting off.

Following the success of the latest launch, vehicles with loudspeakers drove through Pyongyang to announce the “momentous event”. An official statement said that North Korea had exercised the “independent right to use space for peaceful purposes” by placing a satellite into an orbit that will take it over both poles.

The test occurred shortly before the first anniversary of the death of Kim Jong-il, the previous leader, on Dec 17 last year. He was succeeded by his son, Kim Jong-un, who now rules North Korea. Britain summoned the North Korean ambassador to the foreign office to hear a formal protest against this “provocative action”.

Ban Ki-moon, the UN secretary general, denounced North Korea’s action, saying it was “all the more regrettable because it defies the unified and strong call from the international community”. Kim Sung-hwan, the foreign minister of South Korea, said: “This launch is a clear violation of the UN Security Council resolutions…. and a threat to peace to the Korean Peninsula and around the world.”

Even China, North Korea’s only significant ally, voiced “regret” that the country had defied the rest of the world and carried out the test. But vociferous support came from Iran, with Gen Masoud Jazayeri, deputy commander of the armed forces, offering congratulations to the “people and the government” of North Korea on “the successful launching of the satellite-carrying rocket”.

He added: “Dominant powers, like the United States, cannot halt the progress of independent states, who through resistance can quickly tread the path of scientific and technological self-reliance.”