SEOUL: North Korea issued its most strident warning in months on Friday when it threatened to open fire on South Korean territory if anti-Pyongyang leaflets were sent over from South Korean territory.

It said that if leaflets were dropped on Monday a "merciless military strike by the Western Front will be put into practice without warning", according to state news agency KCNA.

It said it would target a tourist area in the border city of Paju a few miles from the demilitarised zone that separates the two countries if the launch went ahead.

A coalition of non-government groups said it would go ahead with plans to drop anti-North Korea leaflets on Monday at 11:30 a.m. (0230 GMT) as part of their campaign against Pyongyang.

North Korea shelled a South Korean island almost two years ago, causing civilian deaths. In 2010, the North was widely blamed for sinking a South Korean navy ship, although it denied responsibility.

KCNA frequently carries anti-South Korean rhetoric, although a specific threat to an exact area has been rare in recent months.

"The KPA (Korean People's Army) never makes any empty talk," KCNA quoted military commanders as saying.

The leader of a coalition of groups comprising North Korean exiles and human rights activists said they intend to go ahead with the plan to send giant balloons containing 200,000 leaflets criticising North Korea's government.

"We had similar threats last year and they did not stop us before and this is not going to stop us this time," said Pak Sang-hak, a North Korean exile who defected to the South 12 years ago.

Pak and his colleagues plan to put 1,000 $1 notes in the leaflets inside plastic bags. They say the U.S. dollars are prized by the impoverished people of North Korea.