North Korea has said it does not want Japan to take part in any future talks on Pyongyang's nuclear programme.
N Korea's neighbours want to address its nuclear ambitions
Japan was one of six nations that gathered in Beijing in August for historic multilateral negotiations on the crisis.
But North Korea's official news agency said on Tuesday that Japan had introduced other bilateral issues into the talks and was no longer "a trusty dialogue partner".
Japan wants North Korea to address the issue of Japanese nationals kidnapped by Pyongyang in the 1970s and 80s.
The BBC's Charles Scanlon in Seoul says Pyongyang's move may be an attempt to derail the talks altogether.
Japan's Foreign Ministry was quick to reject the North's statement, saying Pyongyang was in no position to ban Tokyo from talks.
"Japan is simply entitled to participate in any multilateral talks dealing with the North Korean nuclear issue because... it is a direct threat to Japanese security," foreign ministry spokesman Hatsuhisa Takeshima told the BBC.
"Having Japan at the talks is not only for the Japanese benefit, but also it is essential for North Korea to have a relationship with Japan in the full diplomatic way," he said.
Snatched in the '70s and '80s
Used as cultural trainers for N Korean spies
Five allowed home last year
Their children still in N Korea
Eight said to be dead, others missing
A statement by the North's KCNA news agency said: "Japan is nothing but an obstacle to the peaceful settlement of the nuclear issue between the DPRK [North Korea] and the US.
"It has lost its qualification to be a trustworthy dialogue partner."
It said the abduction issue had already been settled during a summit between North Korea and Japan last year and that linking it to the nuclear talks "only renders the nuclear issue more complicated".
KCNA added that Japan and North Korea's relations had also been damaged by Japan's "lead" in a move to "blockade" Pyongyang.
Tokyo is currently taking part in the 11-nation Proliferation Security Initiative - a series of military exercises which practise intercepting shipments of weapons of mass destruction.
Members of the grouping insist it is not targeting specific countries, but correspondents say North Korea is clearly within its sights.
The KCNA statement added that Tokyo's government had tacitly approved recent moves against North Korea's de facto representative office in the country - the general association of Korean residents in Japan, or Chongryon.
Last month, Tokyo authorities seized three premises belonging to Chongryon, including its headquarters, reportedly because it had failed to pay hundreds of thousands of dollars in tax
North Korea has always pushed for bilateral talks between itself and Washington, in preference to multilateral talks.
But the US is keen to enlist the help of North Korea's neighbours in addressing the nuclear crisis.
It took months to organise the first round of six-party talks, and when they did take place, they did not result in any substantive progress other than an agreement by the participants to meet again.
Leaders from China, Japan and South Korea met on the sidelines of a regional forum in Bali on Tuesday and pledged to continue to work together to resolve the crisis.
"The three countries will co-operate together to keep peace and security," a statement from the South Korean Government said.
North Korea has made a number of confrontational statements over its nuclear programme in recent days, suggesting it might be preparing for another round of negotiations.
Last week, it said it had reprocessed 8,000 spent nuclear fuel rods and was technically ready to use the plutonium extracted from them for weapons purposes.
Western experts believe the rods could yield enough material to build up to six nuclear bombs.