(Reuters) -Credit Suisse Group AG said on Thursday it intended to borrow up to 50 billion Swiss francs ($54 billion) from the Swiss National Bank in what it called "decisive action" to boost its liquidity.

The planned move came after Swiss regulators pledged a liquidity lifeline to Credit Suisse in an unprecedented move by a central bank after the flagship Swiss lender's shares fell by as much as 30% on Wednesday.

"Credit Suisse is taking decisive action to pre-emptively strengthen its liquidity by intending to exercise its option to borrow from the Swiss National Bank (SNB) up to CHF 50 billion under a Covered Loan Facility as well as a short-term liquidity facility, which are fully collateralized by high quality assets," Credit Suisse said in a statement.

It pointed to its end-2022 Common Equity Tier 1 capital ratio of 14.1% and average liquidity coverage ratio (LCR) of 144%. The latter had improved to about 150% by March 14, it said.

Referring to the intended borrowing, it said: "This additional liquidity would support Credit Suisse's core businesses and clients as Credit Suisse takes the necessary steps to create a simpler and more focused bank built around client needs."

The collapses in the U.S. of Silicon Valley Bank last week and Signature Bank two days later have sent global bank stocks on a rollercoaster ride.

Gary Ng, senior economist at Natixis Corporate and Investment Bank, said investors might be worried about Silicon Valley Bank and Credit Suisse for different reasons, but both suffered from the side effect of high-interest rates.

"The underlying economic stress may emerge more frequently ... and it is possible to see more black swans in an uncertain environment," he said.

The Swiss lender's latest move came after CEO Ulrich Koerner said in an interview earlier on Wednesday that the bank's "capital, our liquidity basis is very very strong."

"We fulfill and overshoot basically all regulatory requirements."

Credit Suisse Group last month reported its biggest annual loss since the 2008 global financial crisis after rattled clients pulled billions of dollars from the bank. It warned that a further "substantial" loss would come this year.

The bank, Switzerland's second biggest, has begun a major overhaul of its business, cutting costs and jobs to revive its fortunes, including creating a separate business for its investment bank under the CS First Boston brand. The bank raised 4 billion Swiss francs from investors in December.