North Korea laid out onerous conditions Thursday for any talks with Seoul or Washington, including the withdrawal of UN sanctions and a guaranteed end to South Korea-US joint military drills.
"If the US and the South enemies... genuinely want dialogue and negotiation, they should take these steps," the North's National Defence Commission said in a statement.
The conditions are almost certain to be rejected outright by both South Korea and the United States, which have themselves made dialogue conditional on the North taking steps towards denuclearisation.
The Commission's statement was the North's latest salvo in a heated exchange over the dialogue issue, which has become the new focus of a rhetorical battle that has raised tensions on the Korean peninsula to their highest level for years.
South Korea's new president, Park Geun-Hye, has made tentative -- and conditional -- offers of talks, which received the backing of US Secretary of State John Kerry during his recent Northeast Asia tour.
Both Park and Kerry stressed that any talks would have to be substantive and predicated on signals from North Korea that it "change its ways" and respect its international obligations, especially with its nuclear programme.
UN chief Ban Ki-moon urged Pyongyang on Wednesday to "seriously" consider Seoul's offer, but the conditions listed by the Commission amounted to a vocal rejection.
"The first step will be withdrawing the UN Security Council resolutions cooked up for ridiculous grounds," the statement said.
North Korea has repeatedly cited the UN sanctions imposed after its rocket test in December and nuclear test in February as the prime trigger for the current crisis on the Korean peninsula, which has seen Pyongyang threaten both the United States and South Korea with nuclear attack.
The North's other main bone of contention has been ongoing joint South-US military drills which have involved the deployment of nuclear-capable B-52s and B-2 stealth bombers.
"Second, you need to tell the whole world that you will not get involved in any rehearsal for a nuclear war that threatens our nation. Dialogues and war games can never go together," Thursday's statement said.
It also called for the withdrawal of all "US tools" for a nuclear war from the Korean peninsula and a promise never to deploy them again.
The Commission statement was issued hours after the North's main body for inter-Korean relations ruled out any immediate return to the negotiating table.
The South's dialogue offer is a "deceptive artifice" designed to appease public opinion and to hide its responsibility for pushing the peninsula "to a state of war", the Committee for the Peaceful Reunification of Korea said.
Neither statement made any mention of a possible medium-range missile test -- the expectation of which has kept South Korean and US forces on heightened alert for the past week.
Intelligence reports suggest the North has two Musudan missiles primed to fire from its east coast, and most observers had predicted a launch on or around April 15, the birthday of the North's late founder Kim Il-Sung.
The Musudan, which has never been tested, has an estimated range of up to 4,000 kilometres (2,485 miles).
That would cover any target in South Korea and Japan, and possibly even US military bases on the Pacific island of Guam.