Citi says 'Brexit' would lop 4 pct pts off UK GDP growth, hit pound 15-20 pct

LONDON, Feb 5 (Reuters) - Economic growth in Britain would be up to four percentage points lower over the next four years and sterling could lose a fifth of its value if the country votes to leave the European Union, economists at U.S (Other OTC: UBGXF - news) . bank Citi said on Friday.

So-called 'Brexit' would likely trigger "significant" economic weakness for Britain, hit sterling and send inflation sharply higher, it said.

The report said Citi would cut 1-1.5 percentage points off our its annual growth forecast for 2017, 2018, and 2019, "a total GDP loss of 4 percent, with sterling's trade-weighted exchange rate probably retesting the lows after the 2007-09 crisis...roughly 15-20 percent below current levels."

A plunge in sterling would raise inflation, which has been virtually zero for the past year, to 3-4 percent for several years, they added.

Prime Minister David Cameron has promised to hold a referendum before the end of 2017 but a date this summer is increasingly expected.

Earlier this week, U.S. bank Goldman Sachs (NYSE: GS-PB - news) also said the pound could lose up to 20 percent in the event of a vote for Brexit. (Reporting by Jamie McGeever; Editing by Mike Dolan)