Russia urged the Democratic People's Republic of Korea on Monday to rethink its plan to launch a rocket later this month, as the Republic of Korea said Pyongyang has installed the first stage of the rocket.

"We urgently appeal to the government (of the DPRK) to reconsider the decision to launch a rocket," the Russian Foreign Ministry said in a statement.

Pyongyang had been warned not to ignore a United Nations Security Council resolution, which "unambiguously prohibits (it) from launching rockets using ballistic technology", said the statement.

The DPRK announced on Saturday the decision to launch another satellite and reportedly told neighbors it would take a similar path to the failed rocket launch in April.

Pyongyang insisted it will fully comply with relevant international regulations, but Washington said the planned launch, similar to the attempt earlier their year, is a disguised test for long-range missile technology designed to strike the US.

The DPRK said it gave the US direct notification of its plan to fire a long-range rocket last week, Yonhap News Agency reported.

The DPRK has installed the first stage of the rocket onto the launch pad, which means it is starting process of launching a long-range missile, an ROK government source said on condition of anonymity.

The launch has triggered serious concerns from its neighbors. China urged "all sides" not to take any action that "worsens the problem".

"Under the present circumstances, we hope all sides can be calm and restrained and not take any moves to worsen the problem. China will remain in touch and coordinate with all sides," said Foreign Ministry spokesman Hong Lei on Monday.

Meanwhile, the ROK and Japan prepared to take countermeasures against the launch.

ROK Defense Ministry spokesman Kim Min-seok said the military is closely watching all activities with regard to DPRK's long-range rocket while firmly maintaining military posture and joint alert status with the US military.

ROK chief nuclear envoy Lim Sung-nam was scheduled to meet ambassadors from China, Russia and Japan on Monday to discuss the planned launch, AFP reported.

Lim also plans to visit the US on Tuesday for talks with his US counterpart, Glyn Davies, and the visit will focus on how to respond to the upcoming launch, AFP said.

In Japan, Prime Minister Yoshihiko Noda on Monday called for close cooperation with the US, China, ROK and Russia.

Tokyo has begun deploying a surface-to-air missile defense system and is putting its armed forces on standby ahead of Pyongyang's launch, while Japanese public broadcaster NHK reported that a naval vessel carrying Patriot Advanced Capability-3 ballistic missiles left a western Japan naval base on Monday.

Japanese officials are preparing to issue an advance order as soon as on Friday to shoot down the rocket if it looks set to fall on Japanese territory, after an emergency meeting chaired by Noda, Nikkei business daily reported.

A Japanese Defense Ministry spokesman told AFP that "our ground, marine, and air forces are now preparing to deploy troops in Okinawa", where the rocket may fly over.