North Korea has told a British-based organisation that the planned launch of its satellite will go ahead between April 4 and 8, according to reports.

South Korea's Yonhap agency, quoting a Seoul intelligence source, said that the North had informed the International Maritime Organisation (IMO), based in London, of its early April schedule for the satellite launch.

The North's state run Korean Central News Agency confirmed today that Pyongyang had given the IMO, the International Civil Aviation Organisation and other world bodies "necessary information for the safe navigation of planes and ships" as part of preparations for launching "an experimental communications satellite".

The Times was unable to confirm with the IMO whether it had been given a date for the launch.

South Korean and US officials believe that the launch is a disguised missile test and that the North is preparing to launch a powerful intercontinental missile, the Taepodong-2, capable of carrying warheads as far as the west coast of the US.

Hillary Clinton, the US Secretary of State said in Washington yesterday that "a range of options" could be pursued against North Korea if it tests a long-range ballistic missile, including seeking action in the UN Security Council.

America could seek additional UN sanctions, or a tightening of existing measures. It could also suspend aid promised to the North in a separate nuclear disarmament deal or impose unilateral punishments, analysts have said.

North Korea said that it had acceded to an international treaty on space exploration "as part of its preparations for launching Kwangmyongsong-2, an experimental communications satellite", KCNA reported. Agencies had been informed of its plans so aircrft could be alerted, it said.

Over recent weeks Pyongyang has raised tensions in the region, putting its forces on combat alert and threatening military action against South Korean airliners in protest at joint military exercises between South Korea and the US, which it sees as a rehearsal for an invasion of the North.

However he US intelligence chief said this week that the "satellite launch" might turn out to be just that. Dennis Blair, the National Intelligence Director, told the Senate Armed Services Committee: "The North Koreans announced that they were going to do a space launch and I believe that that's what they intend."

One of the factors tipping the scales toward a possible satellite launch is South Korea's push to launch its two-stage Korea Space Launch Vehicle-01 as early as June.

US intelligence analysts see the launch by North Korea as an attempt to get one over the South while sending a message to Japan and the United States, an intelligence official told AP.

Even if the rocket did carry a satellite, the military implications of rocket technology in the hands of North Korea are alarming, especially in light of its nuclear tests. The technologies of space launch rockets and long missiles are almost identical. Master one and the other was not far behind, Mr Blair said.