ZURICH, March 21 (Reuters) - The Swiss National Bank called on Thursday for adjustments to the regulation of systemically important banks in the aftermath of Credit Suisse's collapse, so they have enough funds to cope with crises and authorities can act early to stabilise them.

"Banks' liquidity provisions should be improved," SNB vice chairman Martin Schlegel said in a speech after the central bank surprised markets with an 25 basis-point interest rate cut.

"At the same time, banks should be required to prepare significantly more collateral."

Schlegel also said banks' equity should be structured in a way that losses could be better absorbed.

Chairman Thomas Jordan, speaking later with Reuters, said it was very important to have clarity about the true level of capital within a bank and that it accurately reflected risks the bank was exposed to.

The SNB played a major role in Credit Suisse's rescue last year, providing 168 billion Swiss francs ($187.00 billion) in emergency liquidity to smooth its takeover by UBS, though some critics argued the 167-year-old institution could have been saved if the central bank acted sooner.

International bodies have also raised concerns about the size of the newly enlarged UBS, whose assets dwarf the economic output of Switzerland, and the risks it poses to the Swiss economy and global financial stability.

The Organisation for Economic Cooperation and Development (OECD) last week said the enlarged bank needed to meet stricter regulatory requirements.

The Financial Stability Board, a grouping of central bankers, treasury officials and regulators from the group of 20 top global economies, has also urged Bern to strengthen its banking controls.

In its annual report published on Tuesday, the SNB said Switzerland needed rules that recognised that UBS, has gained in its systemic importance.

The Swiss government is expected to publish next month its own recommendations on how to deal with banks that are "too big to fail".

Asked if the SNB should play a more active role in bank regulation, Jordan said he thought the current system worked well.

"The advantages must be really big in order to change a working system." ($1 = 0.8984 Swiss francs) (Reporting by Noele Illien, additional reporting by John Revill, Editing by Miranda Murray and Tomasz Janowski)