New York - The UN Security Council remains concerned by the impacts of North Korea's intention to fire a long-range rocket and may convene to debate the event if necessary, a UN official said Thursday.

The council president, Mexico's UN Ambassador Claude Heller, said several members on the 15-nation panel, including Japan, have called for a possible meeting if the rocket is launched.

Unnamed US officials told CNN that Pyongyang was fuelling the rocket to prepare for the launch.

"For the time being, the Security Council can only follow closely without prejudging when this event will take place," Heller told reporters. "But there is a concern by several delegations that, if there is a need of action by the international community, they will ask for a meeting."

Japan, which feels threatened by the North Korean rocket, has warned that it will extend its trade sanctions against the Pyongyang regime. The sanctions are set to expire April 13.

Japan "aims to reinforce its stance in seeking progress in dialogue" with North Korea by extending sanctions for another year, Chief Cabinet Secretary Takeo Kawamura said at a press conference in Tokyo. (dpa)