SEOUL - The Republic of Korea (ROK) deployed an advanced tactical missile system capable of hitting Pyongyang, capital of the Democratic People's Republic of Korea (DPRK), a government source said on Friday, after tensions rose last year.  

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The missiles, with a range of 165 kilometers that can be nearly doubled when modified with boosters, were deployed near the demilitarised zone that divides the Korean peninsula after the North's bombardment of a southern island last year, the source with direct knowledge of the matter said.

"Some of the tactical surface to surface missiles have been deployed in forward areas," the source, who could not be named for national security reasons, said.

The shelling of the Yeonpyeong island in disputed waters off the west coast of the Korean peninsula killed four people including two civilians and drove the two Koreas' ties to the lowest point in decades.

The two sides remain technically at war under a truce ending the 1950-53 Korean War.

The ROK's Yonhap news also reported the missile deployment saying it aimed at deterring attacks by the DPRK following the shelling of the island using long-range artillery.

The office of ROK's Joint Chiefs of Staff declined to confirm the deployment or elaborate on the missile system, but an official said: "The operation of our capabilities will be conducted with flexibility."

Under a defense agreement with the United States, the ROK is restricted from developing ballistic missiles with ranges beyond 300 kilometers.  

Earlier this month the DPRK fired a short range missile into waters off its west coast.

However, the ROK's latest missile deployment is mainly intended to counter the North's multiple rocket launch systems and long-range artillery deployed north of the border, the government source said.  

He declined further technical descriptions citing the sensitive nature of the operation.

The attack on the Yeonpyeong island followed the sinking of a ROK navy ship in March last year killing 46 sailors, which Seoul has blamed on Pyongyang. DPRK denies involvement.

The ROK has demanded an apology from the DPRK as condition for resuming dialogue, but has also sought to engage the neighbour in high-level talks to appease tension and press for disarmament.

The DPRK has rejected the overtures and said it has no hopes for dialogue with the current government in the ROK, in a likely sign that it plans to wait out the term of conservative President Lee Myung-bak, whose term runs until early 2013.