Mr Yam said Hong Kong's fifth-biggest bank by assets had sufficient funds to meet the needs of its customers. Its capital adequacy ratio, which measures a bank's ability to absorb losses and protect depositors, was almost double that required.

Financial Secretary John Tsang Chun-wah rejected the rumours as unfounded and malicious.

The bank's finances were sound 'and there is no problem at all', he said. 'The BEA does not need our assistance but we will fully support it if there is any need.'

Bank chief David Li Kwok-po, who returned to Hong Kong last night from New York, was asked whether he thought the originators of the text messages wanted to affect its share price by spreading negative rumours. He said he did not know, and denied BEA was in any trouble. Its shares closed down 6.85 per cent.

'I plan to buy back some Bank of East Asia shares,' Mr Li said.

A senior banking source said Cheung Kong Holdings chairman Li Ka-shing had pledged his support to BEA and had bought the bank's shares heavily yesterday.

BEA executive director Joseph Pang Yuk-wing also flatly denied there was any truth to the 'malicious rumours' and said the police were investigating.

Mr Yam said the depositors had nothing to worry about.

'They are very well protected because the banking system is very robust. Of course, there is also the deposit protection scheme,' he said.

'They should put their hearts at ease.'

A senior government source said all banks in Hong Kong were financially sound. The Monetary Authority had their financial details but there were practical difficulties in releasing the information since it would invite unnecessary comparisons, the source said.

The assurances cut little ice with BEA depositors.

'It's not normal what is happening in the world. Who knows if what they are saying is true?' said one man queuing to hear directly from bank staff that BEA was safe.

'I have lost confidence in BEA,' said a nine-year customer of BEA in Kwun Tong.

More than one customer said: 'I just want my money.'

Two other local lenders, DBS and Dah Sing Bank, were forced to deny similar rumours yesterday that they were in trouble. Insurer AIA Hong Kong said a letter, purportedly from its customer services department, saying its troubled parent company AIG had decided to sell its Asian businesses was false and fraudulent.

BEA said it had exposures of HK$422.8 million to bankrupt US investment bank Lehman Brothers and HK$49.9 million to AIG, mainly through collateralised debt obligations, the instruments through which the US subprime mortgage crisis spread round the world.

Mr Pang said news of the rumours reached the bank as early as Monday. When customers began withdrawing funds on Tuesday, the bank reported the rumours to the authority and the police.

However, as the rumours spread, nervous depositors began queueing at its major branches yesterday afternoon. Opening hours were extended.

Mr Pang said: 'People can withdraw as much money as they have in their account. There is no upper limit.'

Last week, the bank restated its first-half results to account for a loss of HK$93 million an equity derivatives trader had concealed.

The incident prompted concerns about the bank's internal controls and operational risks, and triggered ratings downgrades. These make it more expensive for a bank to borrow.

Additional reporting by Maria Chan and Natalie Chiu

The Bank of East Asia by the numbers

Total consolidated assets: HK$396b

Total deposits: HK$308b

Loan-to-deposit ratio: 79.7%

BEA's capital adequacy ratio: 14.6%

Minimum required ratio: 8%

BEA's liquidity ratio: 40%

Minimum required ratio: 25%

Source: BEA