Six major powers held yet another inconclusive bargaining session on North Korea's long-range rocket launch as a senior Japanese official pressed for a speedy, "adequate" response.

Envoys of the five permanent members of the UN Security Council ? Britain, China, France, Russia and the United States ? plus Japan huddled behind closed doors for 45 minutes.

But they did not announce a breakthrough in their bid to agree on a text in response to Sunday's launch of a three-stage Taepodong-2 rocket over Japan.

"We had a productive meeting," US Ambassador to the UN Susan Rice would only say after the meeting. "Our work continues."

Her Japanese counterpart Yukio Takasu also described the talks as "productive" and said the six ambassadors "agreed to continue the consultations" on what he called a "very serious act by the DPRK (North Korea)."

But there was no word as to when the six or the full 15-member council would next convene.

Japan's foreign affairs state secretary Shintaro Ito told reporters earlier: "We will continue maximum efforts to (secure) a resolution" stating that North Korea violated UN resolutions barring it from conducting any missile-related activities.

He stressed the need for "adequate action" by the council "with speed and consensus." He would not elaborate on the context of the proposed text.

Ito spoke after holding what he described as "constructive" talks with the current chair of the 15-member council, Ambassador Claude Heller of Mexico.

The Japanese diplomat said he also conferred with the US and Russian ambassadors and planned to meet with Chinese ambassador Zhang Yesui.

Ito said he planned to stay in New York "as long as it takes."

But there was no sign that the council was getting any closer to agreeing on either a resolution or even a weaker, non-binding statement on the issue.

North Korea insists that its rocket put into orbit a communications satellite that is beaming back patriotic songs.

South Korea, Japan and the US military say there is no sign of the object in space and that the launch was in any case a disguised long-range missile test in violation of UN resolutions.

Ito noted that the three-stage delivery system used in Sunday's launch was "a missile itself or used missile technology," which is a violation of UN resolutions adopted in 2006 after North Korea's nuclear test and missile launches.

The United States and its allies are seeking a strong UN response to the launch but China and Russia are urging restraint so as not to harm prospects for resuming stalled six-party talks on North Korea's nuclear disarmament.

Diplomats said China and Russia were balking at the adoption of a resolution and instead would prefer agreement by consensus on a non-binding statement expressing concern about the launch, as well as urging Pyongyang to return to the six-party talks and respect UN resolutions.

Pyongyang has warned of "strong steps" if the United Nations censures it.