ZURICH (Reuters) - UBS plans to overhaul its wealth management business in the United States, splitting the operation into six divisions and focusing more on clients that are not super wealthy, according to an internal memo and a media report on Tuesday.

The memo, seen by Reuters and the authenticity of which was confirmed by the bank, reflects the Swiss lender's efforts to improve its performance in the United States.

According to the Wall Street Journal, which first reported the shake-up, UBS plans to devote more resources in the U.S. to affluent and not quite ultra-wealthy clients.

Under the changes, which will be effective from Jan. 1, UBS will switch its wealth field structure from two national divisions to four regions, in addition to its UBS International and Wealth Advice Center arms, according to the memo.

"This new alignment will empower our field leaders through faster decision-making, enhanced responsiveness to client needs, and greater connectivity," the memo says.

UBS CEO Sergio Ermotti has described the United States as one of the bank's key engines of growth, but said in September the business was not as profitable as it should be.