ZURICH, Sept 21 (Reuters) - The Swiss National Bank will provide liquidity to commercial banks secured against mortgages, Vice Chairman Martin Schlegel said on Thursday.

"No matter their size, banks can find themselves in a situation where they need significant liquidity quickly," said Schlegel, citing risks, such as general uncertainty in the banking sector or cyber attacks on individual lenders.

(Reporting by Noele Illien Editing by Tomasz Janowski)