UBS stable, needs more time to return to profit-CEO

* Crisis not over, sees more writedowns for banks

* New Swiss rules could put big banks at disadvantage

ZURICH, Sept 25 (Reuters) - Swiss bank giant UBS(UBSN.VX) is now stable and working towards profitability, but that will take some time, Chief Executive Oswald Gruebel said on Friday.

"The bank has stabilised," Gruebel said in a speech, adding that the focus was now on returning to profit. "That will still take some time," he added.

UBS, which was hit hard in the crisis, has put a U.S. tax litigation behind thanks to a settlement in August.

Gruebel pointed to the fact that the global financial crisis, which has hit many banks hard, was not yet over.

He noted that economists from the International Monetary Fund and from UBS itself estimated a total of $2.5 trillion of writedowns for the whole banking sector.

"Up until now, the banks have done almost the half of it, that is $1.1 trillion," he said. "More than a half (of these writedowns) is still ahead of us," he added.

Speaking about regulation, Gruebel said proposed new capital and liquidity rules could put Switzerland's two largest banks, UBS and Credit Suisse (CSGN.VX), at a competitive disadvantage if only applied to the two large Swiss lenders.