China hosted the talks that secured the deal offering North Korea diplomatic and economic incentives to disable its main nuclear facility and declare all related programmes.

Officials involved in the talks said Pyongyang itself set Thursday as the deadline to deliver the report to Beijing.

The Chinese foreign ministry could not confirm whether the declaration would be handed over as planned or how it would be announced.

US terror list

White House officials said on Wednesday that North Korea could be removed from the US list of terrorism sponsors once the declaration was delivered.

"Remember, this was action for action, and this was something that was laid out quite a while ago," Dana Perino, a White House spokeswoman, said.

Removal from the list would ease international trade and financial restrictions, and pave the way for improved ties between Pyongyang and Washington.

Japan has expressed unease over the North being taken off the US blacklist before the issue of its citizens kidnapped by Pyongyang is resolved.

Tokyo is expected to raise the issue with Condoleezza Rice, the US secretary of state, when she attends a G8 foreign ministers' meeting in Japan on Thursday.