By Carol Giacomo, Diplomatic Correspondent
WASHINGTON (Reuters) - Contrary to published reports, the United States has seen no signs that North Korea has begun to shut down its Yongbyon nuclear facility as called for in a February 13 six-country agreement, a senior U.S, official said on Tuesday.
News reports in South Korean media are "just not accurate ... We have seen no actions on the North Koreans' part that at this point leads us to believe they are fulfilling their part of the 60-day actions," said the official, who spoke on condition of anonymity.
The official also said there was no indication the North had yet collected $25 million from Macau bank accounts that were frozen as a result of U.S. action and then released as part of the February 13 deal which required Pyongyang to shut down and seal the Yongbyon facility.
"We're puzzled," the official told Reuters.
He said that North Korea, frustrated by the complex international financial system and the difficulties in trying to resolve the frozen funds issue, may fear that claiming the money would trigger new hurdles.
Pyongyang also may want assurances that the release of the $25 million held by Macau's Banco Delta Asia bank will mean it will once again have easy access to the international financial system, the senior U.S. official said.
"I don't know the answer to that ... That's beyond the February 13 agreement ... How they interact with the rest of the financial world is something they have to work on," he said.
In the initial 60-day phase of the February 13 accord, the United States promised to release the $25 million and Pyongyang agreed to shut down its nuclear reactor and invite U.N. inspectors to resume monitoring at the Yongbyon complex.
But Pyongyang missed an April 14 deadline set in the deal by the two Koreas, China, Japan, Russia and the United States.
South Korean media reported earlier on Tuesday that the North may have begun the shut-down. A major daily newspaper, Dong-A Ilbo, citing a diplomatic source, said U.S. spy satellite photographs showed increased activity around the North's Soviet-era Yongbyon reactor.
Yonhap news agency quoted an unnamed intelligence official as saying the reactor was still operating, but there were some unusual signs of activity such as increased vehicle movements.
Chinese Foreign Ministry spokesman Liu Jianchao told a news conference that "technical issues" remained on the funds.
But the senior U.S. official said from an American perspective "every box has been ticked" in an effort to resolve the issue, which Pyongyang cited as its key condition for returning to the six-country talks.
He said Washington had gone to great lengths to explain to the North Koreans the process and rationale for releasing the funds.
This was the main focus of six meetings that the White House's top Asia expert, Victor Cha, had with North Korean negotiator Kim Gae Gwan when Cha was in Pyongyang for three and a half days recently as part of a delegation led by New Mexico Gov. Bill Richardson, a Democratic presidential contender, the official said.
Afterward, Richardson said Pyongyang had made a strategic decision to dismantle its nuclear program but the U.S. official said the administration view is "we still don't know" what the North intends to do.
North Korea has said it could invite U.N. nuclear inspectors into the secretive nation within 24 hours after it sees the problem as solved, a U.S. official who visited Pyongyang said.
U.S. officials and analysts have estimated that shutting down the reactor could take between a few days to about two weeks, depending on the condition of the facility.

Copyright 2007 Reuters Limited.