In Beijing, delegates from six nations have wrapped up a second day of nuclear discussions.

No details are coming out of the working group sessions aimed at defusing an international standoff over North Korea's nuclear weapons program.

Japan's Kyodo news agency said chief U.S. delegate Joseph DeTrani was expected to hold a rare one-on-one meeting with his North Korean counterpart, Lee Geun, on the sidelines of the meeting.

After Wednesday's first sessions, a Russian negotiator said the U.S. and North Korea toughened their stances, with neither side willing to budge from their earlier positions.

North Korea wants compensation and non-aggression guarantees for dismantling its nuclear weapons program, but Washington insists the North must first commit to a full and irreversible dismantlement of its nuclear facilities.

Even as representatives from the two Koreas, the U.S., China, Japan and Russia huddled behind closed doors, North Korean media stepped up its rhetoric against the U.S.

On Thursday, the North's ruling Workers' Party newspaper, Rodong Shinmun, accused Washington of preparing to wage war against the North "under the pretext of the nuclear issue."