South Korea has decided to buy hundreds of cruise missiles capable of striking targets such as North Korea's nuclear sites and command posts, reports said Saturday.

The Korea Times and other newspapers said the air-to-surface missiles would be fitted on 21 new F-15 fighter jets Seoul has agreed to buy from Boeing between 2010 and 2012.

A spokesman for the Defence Acquisition Programme Administration said the government had decided to secure "top-of-line air-to-ground guided missiles from abroad" instead of developing them locally.

"No decision has yet been made as to the type and supplier for the missiles," he told AFP.

However, reports said some 400 Lockheed-Martin Joint Air-to-Surface Standoff Missiles, or other missiles of similar capacity which have a range of 400 kilometres (250 miles), would be purchased.

The reports came as inter-Korean relations are cooling, with the North cutting off all dialogue with its neighbour, labelling Seoul's new president Lee Myung-Bak a "traitor."

South Korea's new chairman of the Joint Chiefs of Staff, General Kim Tae-Young, said in March that it would be important for the South to find nuclear sites and strike them in case the North was about to use an atomic bomb against it.

The North interpreted these remarks, made in response to a hypothetical question from a lawmaker in parliament, as hinting at a preemptive military strike.

Lee, a conservative who took office February 25, has angered the North by adopting a tougher line on relations after a decade-long "sunshine" engagement policy under liberal presidents.

He says he will link economic aid to the North's progress in nuclear disarmament and will raise its widely-criticised human rights policy.