(Adds quotes and segment details) SYDNEY, Oct 21 (Reuters) -...

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SYDNEY, Oct 21 (Reuters) - Australia's No. 2 listed private hospital operator Healthscope Ltd (HSO) on Friday said a downturn in hospital visits would hit quarterly revenue, in a surprise announcement that sent its shares tumbling 26 percent for their worst ever intraday fall.

The slowdown had hit revenue growth in the September quarter and, if the trend continued, growth for the hospitals division would be flat year-on-year, Chief Executive Robert Cooke said in a statement ahead of its annual general meeting .

Healthscope shares had plunged 17 percent in mid-morning trade to A$2.44, after initially diving 26 percent in their biggest intraday fall since listing two years ago. The broader S&P/ASX 200 benchmark (xjo) was flat.

Australia's top private hospital operator, Ramsay Health Care Ltd (RHC) also fell, dropping 5 percent.

Private hospitals, which account for most of Healthscope's revenue, have been seen as a safe bet due to Australia's ageing population.

Cooke said the industry's fundamentals had not changed and the "long-term demand outlook for the hospitals division remains strong".

($1 = 1.3108 Australian dollars)