The North is reported to want substantial economic aid
Leaders from South Korea and Japan are to discuss the diplomatic stand-off over North Korea's nuclear programme with Washington later this month, as the US continues to mull Pyongyang's proposals.
South Korea's Blue House announced that President Roh Moo-hyun would visit Washington from 11-17 May.
Japan's Kyodo news agency said President Junichiro Koizumi was expected to meet President Bush at Camp David sometime between 20 and 22 May.
There has been speculation that Washington would be unlikely to make any decision on its North Korean policy until consultation takes place with South Korea and Japan.
The US has not specified exactly what the North Koreans demanded in landmark talks last week, but reports suggest Pyongyang wanted normalised relations with the US and substantial economic assistance in return for an end to its nuclear programme.
Tensions remain high between Pyongyang and Washington following their meeting. On Thursday, North Korea's official news agency accused the US of mounting dozens of spy flights last month.
Oct 2002 - US says N Korea "admits" secret nuclear programme
Nov 2002 - US-led decision to halt oil shipments to N Korea
Dec 2002 - N Korea expels two nuclear watchdog's inspectors
Jan 2003 - N Korea says it is withdrawing from Nuclear Non-Proliferation Treaty
Feb 2003 - N Korea "restarts" Yongbyon nuclear plant
Apr 2003 - N Korea ends insistence on direct talks with US
Washington is reported to have ordered its intelligence agencies to review their monitoring of North Korea after Pyongyang allegedly claimed to have started reprocessing some of its stock of spent fuel rods, which could speed up any nuclear weapons programme.
The New York Times quoted senior administration officials as saying that the White House wants an investigation into whether US intelligence could have missed either a hidden reprocessing plant or one that operates at an undetectably low level.
Seoul and Tokyo are keen that the stand-off with the North is resolved peacefully, and have said that they do not support sanctions against Pyongyang.
Both countries want to take part in any future negotiations with North Korea. Japan has issues of its own to resolve with the Stalinist state.
It wants to press Pyongyang on its demand that the children of five Japanese citizens who were kidnapped by North Korea be allowed to join their parents, now settled back in Japan, and on the alleged abduction of dozens of others.
In a sign on continuing tensions between North Korea and the US, KCNA news agency said on Thursday that "the US imperialists perpetrated at least 220 cases of aerial espionage" in April.
Pyongyang regularly makes such accusations, but this latest was particularly specific.