Japan is to deploy surface-to-air missiles in central Tokyo in readiness for North Korea's planned rocket launch, its defense minister said Monday.

The sitting of an anti-missile battery in the densely packed capital city would be in addition to facilities on the southern island chain of Okinawa Naoki Tanaka told lawmakers.

"We are working on procedures to deploy the Patriot in the Tokyo metropolitan area, acting on precedent," Tanaka told upper house members, referring to the PAC-3 surface-to-air missile defense system.

"We are also preparing to deploy the Patriot in the Nansei (southwestern) islands including Okinawa," as the second stage of North Korea's rocket is expected to fly over Japan's southernmost island chain, Tanaka added.

The nuclear-armed North has announced it will launch a rocket in mid-April to put a satellite into orbit, a move the United States, South Korea and other nations see as a pretext for a long-range missile test banned by the UN.

Tanaka said on Friday he was readying Japan's missile defense systems to shoot down the rocket if it looked set to fall on the country, a move similar to measures Japan took in 2009 before Pyongyang's last long-range rocket launch.

In 2009, Japan ordered missile-defense preparations, including the sitting of one of its PAC-3 systems at Ichigaya, next to the defense ministry building in central Tokyo.

The preparations by Japan, regularly the target of North Korean barbs, come as world leaders including US President Barack Obama are meeting in Seoul for a summit officially focused on nuclear terrorism.

Obama urged North Korea's leaders Monday to "have the courage to pursue peace", while South Korea has said it is also preparing to shoot down the North Korean rocket if it strays into the South's territory.

The 2009 rocket launch, which North Korea said was also aimed at putting a satellite into orbit, passed over Japan without incident or any attempt to shoot it down. (AFP)