North Korea may be preparing to shut down its main nuclear reactor, news reports said Tuesday, renewing hopes it will comply with a disarmament agreement days after missing a deadline to close the facility. Meanwhile, South Korea said it will discuss food aid to the North at economic cooperation talks between the Koreas - despite earlier reports that Seoul was considering halting the shipments in an apparent move to ratchet up pressure on the North, which has requested 400,000 tons of rice. "The issue of food aid will be discussed" at meetings beginning Wednesday in Pyongyang, North Korea's capital, Deputy Unification Minister Kim Jung-tae told reporters. South Korea has periodically sent rice and fertilizer to the impoverished North since an unprecedented 2000 summit spawned reconciliation between the Koreas, but often faces criticism from conservatives here and abroad for being too lenient on its northern neighbor. North Korea's Yongbyon reactor remained in operation Tuesday, but there was a high possibility that movement of cars and people at the site recorded in satellite photos could be linked to a shutdown, South Korea's Yonhap news agency reported, citing an unnamed intelligence official. The Dong-a Ilbo newspaper carried a similar report. An official at the National Intelligence Service, South Korea's main spy agency, told The Associated Press they were "following and analyzing some peculiar movements" around the reactor in North Korea, without elaborating. The official spoke on condition of anonymity, citing policy. Yonhap news agency cited another unnamed intelligence official as saying that South Korea and the United States have been closely monitoring some movements since a month ago. "The intensity of these activities has increased from about a week or two ago," the official was quoted as saying. "There are activities other than cars and people moving busily." The report comes after North Korea missed a Saturday deadline to shut down the reactor and allow UN inspectors to seal the facility under a February agreement with the US and four other countries. If North Korea complies, that would be its first move toward stopping its nuclear program since 2002, when the latest nuclear standoff began. The North is believed to have produced as many as a dozen atomic bombs since then, and conducted an underground nuclear test in October. North Korea said last week that shutting down the reactor was contingent on the release of money that was frozen after Washington blacklisted a bank where North Korea had accounts. The funds were allegedly linked to money laundering and counterfeiting. The US$25 million was freed for withdrawal last week, but it was unclear when North Korea would move to get its funds. South Korean Foreign Minister Song Min-soon spoke by telephone Tuesday with his US counterpart, Condoleezza Rice, and the two "strongly expressed expectations that North Korea will soon implement disarmament measures," the Foreign Ministry said in a statement. Song and Rice "reaffirmed that the door to resolving the (bank) issue is clearly open to North Korea," the statement said. Song also talked by telephone with his Chinese counterpart, Li Zhaoxing, on Tuesday and they agreed to cooperate to help resolve the money dispute quickly, the South's Foreign Ministry said. China said Tuesday that it hoped the bank dispute would be resolved and progress made on disarming the North. North Korea "still needs confirmation on the relevant questions" concerning the financial issue, Foreign Ministry spokesman Liu Jianchao said at a regular briefing. "There are still some specifics the relevant countries are concerned about that need to be further clarified and confirmed." He did not give details. He also said the views of the parties involved in the dispute - the US, North Korea and Macau - were "coming closer," and that Beijing hoped it would be quickly resolved. Separately, a Chinese Communist Party delegation arrived in Pyongyang, North Korea's official Korean Central News Agency reported. No details were given. Alexander Losyukov, Russia's chief delegate to the North Korean disarmament talks, took an upbeat note Tuesday during a visit to Tokyo. "What gives us a certain amount of optimism is that our North Korean colleagues said that they would be prepared to fulfill their obligations" sooner rather than later, Losyukov was quoted by Kyodo News agency as saying after meeting his Japanese counterpart. Meanwhile, Macau's Banco Delta Asia said Monday it had filed a legal challenge to Washington's decision to cut it off from the US financial system. The bank said it told the US Department of the Treasury that its accusations of abetting North Korea's alleged illicit activities "lacked specific facts" and were motivated by politics. In Washington, the US Treasury expressed confidence it would ultimately prevail in the legal challenge.