China has expressed its "deep regret" at a US ruling on a Macau-based bank linked to allegations of North Korean money-laundering and counterfeiting.
The bank has been on a US blacklist since September 2005
The US Treasury said on Wednesday that US banks and companies must sever all ties with Banco Delta Asia (BDA), the subject of an 18-month investigation.
US envoy Christopher Hill said he did not think the move would block progress on a recently agreed nuclear deal.
But it was not clear if Washington's ruling would satisfy Pyongyang.
North Korea had demanded that a freeze on its assets held by BDA be lifted.
"We deeply regret the ruling by the United States," China's foreign ministry spokesman Qin Gang said.
Mr Qin said the US handling of the BDA case should be "conducive to the handling of the six-party talks" and benefit the stability of the Chinese territory of Macau.
"Our position is strong. Our measures are effective. We follow closely the international obligations," he said.
BANCO DELTA ASIA
In September 2005, US labels BDA a "primary money-laundering concern"
Alleges links to N Korean trade in counterfeit US currency, cigarettes and drugs
Alleges front companies laundered millions in cash through the bank
Claims led Macau to freeze some $24m in N Korean-linked accounts
BDA, described as a small, family-run firm, denies any wrongdoing
The bank says it had a dated computer system and lacked the technology to check for counterfeit money
US Treasury Under-Secretary Stuart Levey said on Wednesday that the 18-month probe had confirmed BDA's "willingness to turn a blind eye to illicit activity, notably by its North Korean-related clients".
But while the ruling bars the BDA from accessing the US banking system, it could also allow Macau's authorities to remove the bank from receivership and return some of North Korea's money.
The US accused the BDA in September 2005 of acting as a conduit for money earned by Pyongyang from counterfeit currency and drug smuggling.
Soon afterwards the Macau authorities took control of the bank and froze accounts linked to North Korean clients - said to be worth $25m (£13m).
The US decision led North Korea to boycott talks on ending its nuclear programme for more than a year - only returning to the negotiating table in December after testing missiles and a nuclear weapon.
Pyongyang agreed in February, at a further round of six-party talks in Beijing, to "shut down and seal" its Yongbyon nuclear reactor in exchange for energy aid.
The six parties - the two Koreas, China, the US, Japan and Russia - are due to resume talks on Monday on the progress of the nuclear deal.
Christopher Hill said he was "confident" the talks would go ahead and that the ruling on the BDA would not "pose a stumbling block".
The Macau Monetary Authority said in a statement on Thursday that it expressed "its deep regret" over the US findings, adding that the Macau government "will soon make an official response."
Meanwhile, the BDA's chairman Stanley Au appeared upbeat when asked for his reaction, shrugging off the US ruling.
"Do you think I look worried? I'll take it as it comes," he told a television broadcaster in Beijing, where he is attending a meeting.