The South Korean Navy has rejected North Korea's claim that a South Korean warship intruded into its territorial waters.

The Navy Headquarters said Saturday that it would respond resolutely to any such groundless claims, calling them tantamount to de facto military provocations.

On Friday, North Korea claimed a South Korean battleship had intruded into its waters and warned such actions could provoke what it called "unpredictable consequences."

The North's official news agency, KCNA, claimed the South Korean ship had "perpetrated a grave military provocation by intruding deep into the territorial waters of the North, calling it "an outright challenge" intended to escalate tension between the countries.

This is the fourth time in about two weeks the North has made claims of intrusions by South Korean warships into its territorial waters.

North Korea has never recognised the sea border with the South that was drawn up by a US-led UN Command after the Korean War, and it is a frequent flashpoint between them.