South Korean President Park Geun-Hye on Thursday said a planned rocket launch by North Korea could "never be tolerated," as her defence ministry vowed to shoot down any missile that threatened its territory.

Pyongyang has announced it will launch a satellite-bearing rocket sometime between February 8-25, which is around the time of the birthday on February 16 of late leader Kim Jong-Il, father of current leader Kim Jong-Un.

UN sanctions prohibit North Korea from any use of ballistic missile technology, and such a launch would amount to another major violation of UN Security Council resolutions following its fourth nuclear test last month.

"The fact that North Korea said it will launch a long-range missile following its nuclear test is a threat to peace on the Korean peninsula and to the world, and should never be tolerated," Park said.

The North insists its space programme is purely scientific in nature, but the United States and allies like South Korea say its rocket launches are aimed at developing an inter-continental ballistic missile (ICBM) capable of striking the US mainland.

South Korean officials routinely refer to them as "long-range missiles" rather than space rockets.

The planned launch poses a dilemma for the international community, which is already struggling to find a united response to the North's January 6 nuclear test.

- Harsher sanctions -

North Korea is already subject to numerous UN sanctions over previous nuclear and rocket tests, and Park said its continued provocative behaviour showed these had been ineffective.

The only solution, Park argued, was to impose sanctions harsh enough "to make it realise that it will not survive unless it gives up its nuclear programme."

Russia on Thursday also expressed "grave concern" over the launch, joining a global chorus of condemnation which includes China, traditionally North Korea's chief diplomatic ally.

Moscow's foreign ministry said in a statement that it had summoned the North Korean ambassador and had issued an "urgent appeal to refrain from actions that could further escalate tensions in the region".

Earlier in the day, the defence ministry in Seoul said it had issued orders to destroy any missile that might stray over South Korean territory.

"The military is ramping up its air defence readiness so it can intercept a missile or any debris that lands in our territory or waters," ministry spokesman Moon Sang-Gyun told reporters.

Japan has issued a similar "destroy" order for any North Korean projectile that infringes on its territory.

Japan's public broadcaster NHK reported Thursday that North Korea may be preparing a ballistic missile test from a base on its east coast in addition to the rocket launch.

Citing diplomatic sources it did not identify, NHK reported that it has been "confirmed that a mobile launch pad in North Korea's eastern coastal area was on the move."

As a ballistic missile is on the launch pad, it is possible that Pyongyang is preparing a launch there, the report added.

NHK did not say whether it was a long- or short-range missile.

South Korea's defence ministry said it was unable to confirm the report.