North Korea has moved forward its time frame for launching a long-range rocket into space by one day, the South Korean Defence Ministry said Saturday.
The launch could come any time between Sunday and February 14, the ministry in Seoul said.
North Korea said earlier this week that the launch would send an "Earth observation satellite" into orbit but South Korea and the United States said it is a front for a ballistic missile test, which is banned by multiple UN Security Council resolutions.
China, the isolated country's most important ally, warned Pyongyang the launch could lead to the "escalation of tensions" on the Korean peninsula, while South Korea said it would "pay a harsh price."
The UN had earlier been told that the launch would take place between February 8 and 25. It was unclear if its agencies had been informed of the new dates.
North Korea, which frequently fires short-range missiles into the sea, launched a satellite into space in 2012. The US charged the country with having secretly tested intercontinental ballistic missiles with nuclear capabilities.
The UN Security Council has imposed a host of sanctions against the impoverished communist country since 2006 for its atomic bomb tests.
It claimed to have exploded a hydrogen bomb on January 6, but Western experts say evidence suggests it was more likely to have been a normal atom bomb as an H-bomb has a higher explosive force than what was observed.
Analysts have noted that the upcoming launch would come just ahead of the February 16 birthday of deceased North Korean dictator Kim Jong Il, the father of current leader Kim Jong Un.