North Korea said it may delay a much-criticised rocket launch originally scheduled for as early as Monday, as analysts say its efforts to mark a key anniversary were hampered by technical troubles.

Scientists were "now seriously examining the issue of readjusting the launching time of the satellite for some reasons", the Korean Committee of Space Technology said in a statement carried by state media Sunday.

The committee gave no further details.

Analysts said technical problems or snow, rather than overseas political pressure, are likely to be behind the delay in what the North calls a satellite launch, originally scheduled for between December 10 and 22.

Some said the North's new leader, Kim Jong-Un, may have been rushing the blast-off in a bid to mark the first anniversary of the death of his father and ex-ruler Kim Jong-Il which falls on December 17.

The impoverished but nuclear-armed nation insists the long-range rocket launch -- its second this year after a much-hyped but botched mission in April -- is for peaceful scientific purposes.

But the United States, and allies South Korea and Japan, say Pyongyang plans a disguised ballistic missile test that violates UN resolutions triggered by its two nuclear tests in 2006 and 2009.

"Sunday's announcement was only made by scientific authorities, meaning the most likely reason is either technical issues or weather conditions," said Jang Yong-Seok from the Institute for Peace and Unification Studies at Seoul National University.

A US think-tank, the US-Korea Institute at Johns Hopkins University, said Friday that preparations may have been delayed by heavy snow.

There had been "abnormal signs" indicating technical problems in launch preparations since Saturday afternoon, said South Korea's Yonhap news agency, citing an unidentified senior Seoul official.

"It looks like the problem is a technical one," said the official quoted by Yonhap.

Pyongyang has apparently "rushed too fast" to time the launch to mark the December 17 anniversary in a bid to drum up support for the young and inexperienced Jong-Un, said Yang Moo-Jin of Seoul's University of North Korean Studies.

"It showed how desperate and time-pressed the North was to showcase its scientific breakthrough to its people on the key anniversary and subsequently rally support for the new leader," Yang told AFP.

The North would have made the announcement of a potential delay via "a top party or military organ," instead of the space committee, if it was intended to be a concession to the international pressure, he added.

Another Seoul diplomatic source quoted by Yonhap also said it appeared "very difficult" for Pyongyang to carry out the launch as previously planned given the unusually cautious tone of its announcement.

Kim Jong-Un took over from his late father last December, the second father-to-son power transfer by the Kim dynasty that has ruled the isolated state with an iron fist for some 60 years.

Analysts said the December 10-22 launch window was twice as long as the period set before the failed April launch, reflecting the difficulties technicians may encounter in the harsh winter weather of the Korean peninsula.

Analysis of satellite imagery suggested preparations at the Sohae satellite launch station were proceeding "more slowly than previously reported", the US-Korea Institute said.

Washington and Seoul have urged Pyongyang to scrap the launch while Tokyo has postponed talks originally planned this week with North Korea.

UN diplomats inside and outside the Security Council have reportedly started consultations behind the scenes on what action to take if Pyongyang goes ahead.

Japan, the United States and South Korea have agreed to demand the UN Security Council strengthen sanctions on North Korea to levels that match those on Iran, Japan's Asahi Shimbun newspaper said.