China resisted US-led pressure to bring its ally North Korea to heel for launching a long-range rocket, arguing that any response from the United Nations should be "prudent" and measured.

The United States demanded further action from China -- Pyongyang's foremost patron -- and US allies pressed for stronger sanctions, after the UN Security Council condemned North Korea for carrying out Wednesday's banned launch.

But foreign ministry spokesman Hong Lei told reporters that China believes any UN response "should be prudent, appropriate and conducive to peace and stability on the Korean peninsula and avoid the escalation of the situation".

North Korea says it placed a satellite in orbit for peaceful research, but critics say the launch amounted to a banned ballistic missile test that marked a major advance for the communist state's nuclear weapons programme.

Hong said China "regrets" the rocket launch, but his response fell far short of the much stronger language of condemnation used by the United States, South Korea and Japan, among others.

The United States said Thursday it was working with China to persuade it to back a strong response to North Korea, and denied it had been caught off guard by the launch after earlier reports that the rocket had been dismantled.

State Department spokeswoman Victoria Nuland also warned North Korea against any further such actions, as Pyongyang's state media said that Kim had ordered more satellite launches.

"He has a chance, as the new leader, to take his country back into the 21st century, to take it back into integration with the region and with the world. But he's making the wrong choices right now," Nuland said.

China is considered to have the most influence over North Korea and US officials are scrutinising its policy for any hints of change as Communist Party chief Xi Jinping gradually takes the reins of power.

But Chinese state media downplayed the need for stepped-up sanctions and said that in any case, China has limited influence over Pyongyang.

"The real problem is China's strength is not sufficient to influence its neighbour's situation," the Global Times daily said in an editorial titled "NK move shows China's lack of leverage".

A bellicose Western reaction risked driving North Korea into a corner with potentially devastating results, state editorials said.

"That is why China should not take a cooperative stance with the US, Japan and South Korea in imposing sanctions on North Korea," the Global Times said.

South Korea's defence ministry said the satellite launched by the rocket was in operational orbit, but the main concern in the West is that North Korea may be perfecting technology to fire missiles as far as the US Pacific coast.

Analysts say the symbolism of the launch was also a prime motivating factor for North Korea as the youthful Kim Jong-Un shores up his leadership a year on from the death of his father Kim Jong-Il on December 17 last year.

A previous launch of North Korea's Unha-3 rocket in April was an embarrassing failure, with the carrier exploding after take-off, and the regime was believed keen to mark this month's anniversary with an emphatic success.

China did join other members of the Security Council in condemning the launch as a "clear violation" of UN resolutions.

Diplomats at the council meeting said China's UN ambassador resisted having tougher language in the statement, opposing use of the phrase "ballistic missile technology", but eventually gave in under US pressure.

Masao Okonogi, honorary professor at Keio University, told AFP that China was employing its usual tactic of gentle persuasion with the aim of getting North Korea to open up.

"I think it wants to shift the North toward the opening up of its economy without driving it to the wall. By doing so, it is considering prompting North Korea to transform its structure gradually."

Outrage over Wednesday's launch was mixed with concern that North Korea may follow past practice in following up a missile or rocket launch with a nuclear test.

The North's first nuclear test in 2006 came three months after it tested a long-range missile. On that occasion, Pyongyang announced the test six days before it exploded the device.

The second test, in May 2009, came a month after a rocket launch that North Korea claimed had put a satellite in space.

Pyongyang had threatened a second test unless the UN Security Council apologised for its condemnation of the launch.