Hong Kong injected nearly $500 million (£269 miillion) into the financial system today to shore up liquidity a day after the Bank of East Asia was hit with what appears to be the region’s first big bank run since the global financial crisis erupted last year.

The embattled bank got a boost when Li Ka-shing, the territory’s richest man and a billionaire tycoon, bought the company’s shares after they plunged yesterday. “He did buy Bank of East Asia shares. It’s a personal investment.” a Li spokeswoman said.

Thousands of customers converged on Bank of East Asia offices across Hong Kong yesterday to demand their deposits amid unconfirmed rumours about the bank’s stability. About 200 people lined up at two branches alone. The fear then spread to Singapore, where the crowds had thinned today, although a few dozen depositors were seen at a few branches in the morning.

Bank of East Asia and the Hong Kong authorities were quick to shoot down the rumours, spread by mobile phone text messages in recent days, as “malicious and baseless."

“Bank of East Asia is financially robust,” John Tsang, the Hong Kong Financial Secretary, said today.

The bank, Hong Kong’s fifth largest by assets, declined to specify how much customers had withdrawn but said it was not a large amount and no big clients had pulled their money. It offered assurances that its capital ratio was well above international standards. Seeking to calm investors, the bank also disclosed that its combined exposure to Lehman Brothers and American International Group (AIG), the troubled insurer, was about HK$473 million (£32.8 million).

The rumours emerged after Moody’s Investors Service, the credit rating agency, changed its outlook on the bank's credit rating from stable to negative, citing a recent insider trading case that exposed “lacklustre internal controls at the bank".

Last week, the bank revealed a trading loss of HK$93 million that it said was incurred by a rogue equity derivatives trader, who “manipulated valuations to hide losses". The discovery forced the bank to revise down its earnings for the first half of the year.

The shares were up almost 3 per cent to HK$25.85 today after tumbling more than 7 per cent.

The Hong Kong Monetary Authority, which is effectively the central bank, flushed HK$3.8 billion into the banking system.

The panic underscored a growing distrust of financial institutions in Asia since the turmoil on Wall Street began.

Confidence has eroded in recent weeks as thousands in Hong Kong and Singapore canceled policies with AIG and investors in Lehman Brothers products lobbied the governments to help prevent losses.

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