North Korea warned South Korea on Thursday that a rash of "reckless" incursions at their disputed maritime border could spark a naval clash.
North Korea's navy accused South Korean warships of routinely broaching its territory - 10 times on Monday alone - in the waters off the peninsula's west coast.
"The reckless military provocations by warships of the South Korean navy have created such a serious situation that a naval clash may break out between the two sides in these waters," the military said in a statement carried Thursday by the North's official Korean Central News Agency.
The warning of a clash in the West Sea - site of deadly naval skirmishes in 1999 and 2002 - comes even as relations between the two Koreas show signs of improvement after more than a year of tensions.
On Wednesday, North Korea extended a rare apology to the South for releasing a massive amount of water from a dam near their border last month. Six South Koreans drowned in the flooding.
South Korea's top official for inter-Korean relations, meanwhile, indicated that Seoul is prepared to offer the North food aid without conditions as a humanitarian gesture - an apparent softening of the government's stance toward Pyongyang.
"We will provide limited humanitarian assistance to the most vulnerable groups in North Korea regardless of political and security circumstances," Unification Minister Hyun In-taek said in a speech to the European Union Chamber of Commerce in Korea.
"We will do our part to end the suffering of our brothers in the North," he said.
For a decade, South Korea was one of biggest donors to the impoverished North. But the flow of aid from Seoul stopped when President Lee Myung-bak took office last year, saying any help must be conditioned to denuclearization.
North Korea has faced chronic food shortages since flooding and mismanagement destroyed its economy in the mid-1990s. Famine is believed to have killed as many as 2 million people in the 1990s.
Hyun did not elaborate on a time frame or amount of possible aid to North Korea.
The two Koreas technically remain in a state of war because their three-year conflict ended in a truce, not a peace treaty, in 1953. They are divided by a heavily fortified Demilitarized Zone.
North Korea, however, does not recognize the western maritime border drawn unilaterally by the United Nations, and routinely issues warnings to the South about incursions across the military line.
South Korea, meanwhile, wants to discuss the return of 560 soldiers who have been held by North Korea since the war and 504 civilians, mostly fishermen whose boats have been seized near the maritime border.
North Korea says the civilians voluntarily defected to the North and denies it has any South Korean prisoners of war.
South Korea also wants to stage more reunions of families divided by the war. On Friday, Red Cross officials are to meet in North Korea to discuss staging future reunions.