Report : North Korean jets flew near South 10 times

North Korean jet fighters have tested South Korean defences by flying near the border repeatedly in the past month, prompting Seoul to scramble aircraft in response, news reports said Monday.

Seoul military authorities refused comment on the reports, which come amid a flare-up in tensions.

On Sunday the communist state's official media claimed that Seoul was planning a preemptive military strike and threatened to turn South Korea into "ashes" if it went ahead.

In the past five days the North has expelled South Korean officials from a joint industrial complex, test-fired missiles, accused Seoul of breaching a disputed sea border and threatened to suspend all dialogue.

Chosun Ilbo newspaper quoted military sources as saying the North's jets, including MiG-21s, had flown near the heavily fortified border 10 times since conservative President Lee Myung-Bak was inaugurated in Seoul on February 25.

Jets scrambled each time to intercept the North's aircraft according to their operational rules, said Chosun, the largest-circulation newspaper.

"It is very unusual for North Korean jet fighters to fly southward so intensively in such a short period of time as one month," the paper said.

Chosun also said a North Korean mechanised army unit was recently spotted moving south after a regular exercise in what it called an unprecedented military move.

Yonhap news agency said the North's winter land, sea and air military exercises have increased more than 50 percent this year over previous years.

The North is angry at Lee's tougher stance on cross-border relations, especially his decision to link long-term economic aid to progress in nuclear disarmament and to raise the North's human rights record.

It blames the United States for delays in carrying out a six-nation nuclear pact and said last Friday it may slow down work to disable its atomic plants.

With US negotiator Christopher Hill due in Seoul on Tuesday to discuss ways to restart the stalled negotiations, Washington decried the inter-Korean row.

"Is it directly related to the six-party talks, to the six-party process? No. But is it helpful? I certainly don't think so," State Department deputy spokesman Tom Casey said.

South Korea's military and the defence ministry refused comment on the Chosun report. There was also no official response to Sunday's "ashes" remarks by Pyongyang.

"It truly is unfortunate for North Korea to make such threats but the government sees no need to be alarmed and make an immediate response," a defence ministry official told Yonhap on condition of anonymity.

Analysts believe the North is intent partly on swaying the outcome of South Korea's April 9 general election in which Lee's conservative party is seeking a parliamentary majority.
Late Saturday the North's chief delegate to high-level military talks said all dialogue with South Korea may be suspended and called for an apology over reported remarks by the South's new military chief.

Last week General Kim Tae-Young told parliament the South would strike the North's nuclear sites should the North attack it with nuclear weapons.

The North claims the remarks amount to plans for a preemptive strike, something the South strongly denies.

"Our revolutionary army will counter any slightest move of the South's 'preemptive attack' on our nuclear bases with a more rapid and more powerful preemptive attack," the official Korean Central News Agency said Sunday.

"It should be kept in mind that once our preemptive attack is launched, everything will turn into ashes, not just a sea of flames."

North Korea vowed to turn the South into a "sea of fire" during a previous nuclear crisis in 1993-94.

Choson Sinbo, a pro-North Korea paper published in Japan, said tensions were the worst since the 2006 nuclear test. "The North is firmly responding to the South's provocations," it said.