ZURICH, SWITZERLAND - Switzerland's largest bank, UBS, is losing key staff in important areas to competitors, chairman Kaspar Villiger was reported as saying on Saturday.

"This has reached such an extent in the United States that it's making us think. We're also losing people to the competition in Switzerland but not to such a dramatic extent," the chairman of the world's largest wealth management in terms of assets said in an interview with Switzerland's Berner Zeitung.

"We have to react," Villiger, a former Swiss finance minister, said.

UBS is struggling to rebuild its once powerful brand after massive writedowns on investments into risky U.S. assets forced it to accept government backing.

Current Finance Minister Hans-Rudolf Merz said on Thursday that the Swiss government wants to exit its investment in UBS rapidly but will only do so when the bank is stable and market conditions are favorable.

Villiger, who was appointed UBS chairman in March as part of a management clearout, said he accepted the need for stricter supervision but warned against too much government interference.

"Overregulation that would endanger international competitiveness would be wrong," Villiger said.

"Noticeable tendencies to introduce state wage guidelines would be the most foolish thing for a country like Switzerland," said Villiger, adding that large companies outside the banking sector like Nestle (NESN.VX) would also be hit by less favorable conditions for business.

Facing public anger over what many regarded as excessive bonuses, UBS undertook a radical overhaul of its executive pay system last year after its bet on risky U.S. assets backfired.