ZURICH, March 28 (Reuters) - Regulation of the newly enlarged UBS will be "challenging" for Swiss authorities, the International Monetary Fund said on Thursday, citing the bank's size, complexity and global reach.

"It is challenging and it requires further actions and changes ... in terms of capital and liquidity requirements, and overall too big to fail framework, and those actions will enable a proper supervision and regulation," said Pelin Berkmen, head of the IMF delegation to Switzerland. (Reporting by John Revill Editing by Miranda Murray)