Citing government support, Mr Au said no director from his bank would be prosecuted on a charge of money laundering.

'Delta Asia Group denies that BDA knew or suspected that its customers were engaged in money laundering, or that any of its customers were engaged in any criminal activities, or their funds were in any way connected with such activities,' Mr Au told a press conference in Macau.

The US Treasury Department on Wednesday barred American banks from doing business with the tiny, family-owned Macau bank. The decision followed an 18-month investigation which found the bank had acted to facilitate North Korean counterfeiting of US currency, manufacturing of fake cigarettes and trading in illegal drugs.

Mr Au said he had gone through 18 months of 'mental suffering and great endurance'.

'But I am proud and satisfied that I have handled the case very responsibly,' he said. 'I can stand tall and look squarely at the Macau people and tell them I am a good son of Macau.'

Washington earlier pledged to resolve the freezing of North Korean deposits with BDA as an incentive to bring Pyongyang back to international talks to dismantle its nuclear weapons programme.

Macau authorities can now release between US$8 million and US$12 million of the frozen funds identified as relatively low-risk.

Mr Au said BDA had closed all its North Korean accounts in addition to the frozen accounts.

'We'll never do business with North Korean customers, unless North Korea normalises diplomatic relations with the US,' he said.

Responding to rumours, Mr Au said he was '100 per cent sure' that no BDA directors would face prosecution. 'Mr Tam said we had not violated Macau banking regulations. It was the Macau government's promise to return the control of the bank by the end of March,' he said.

Macau's Secretary of Economy and Finance, Francis Tam Pak-yuen, said on Thursday that his government had found no illegal operations by the bank.

But the US Treasury Department's decision on Wednesday prompted the government to delay the bank's handover indefinitely. The government took control of the bank after its blacklisting by the US in 2005 triggered a run on deposits.

Mr Au said his bank would continue to appeal against the US Treasury Department's sanctions, while seeking further dialogue with it.

'We invited Ernst & Young to investigate our operation. They gave positive results,' he said. 'They believe we never knowingly accepted illegal funds from customers.'

Daniel Glaser, the US Treasury Department's deputy assistant secretary for terrorist financing and financial crimes, will meet top Macau officials today to discuss matters related to BDA.